diff --git a/js/background.js b/js/background.js
index 283365e64..73a18ae64 100644
--- a/js/background.js
+++ b/js/background.js
@@ -106,8 +106,6 @@
 
   window.document.title = window.getTitle();
 
-  // start a background worker for ecc
-  textsecure.startWorker('js/libsignal-protocol-worker.js');
   let messageReceiver;
   Whisper.events = _.clone(Backbone.Events);
   Whisper.events.isListenedTo = eventName =>
diff --git a/js/models/conversations.js b/js/models/conversations.js
index a16f2fe50..80de7e568 100644
--- a/js/models/conversations.js
+++ b/js/models/conversations.js
@@ -1360,7 +1360,11 @@
       let title = i18n('delete');
       let message = i18n('deleteContactConfirmation');
 
-      if (this.isGroup()) {
+      if (
+        this.isGroup() &&
+        !this.get('left') &&
+        !this.get('isKickedFromGroup')
+      ) {
         title = i18n('leaveGroup');
         message = i18n('leaveGroupConfirmation');
       }
diff --git a/libtextsecure/libsignal-protocol.js b/libtextsecure/libsignal-protocol.js
index f34a981a1..dfda09ecc 100644
--- a/libtextsecure/libsignal-protocol.js
+++ b/libtextsecure/libsignal-protocol.js
@@ -25316,77 +25316,6 @@
 
   })();
 
-  ; (function () {
-
-    'use strict';
-
-    // I am the...workee?
-    var origCurve25519 = Internal.curve25519_async;
-
-    Internal.startWorker = function (url) {
-      Internal.stopWorker(); // there can be only one
-
-      Internal.curve25519_async = new Curve25519Worker(url);
-      Internal.Curve.async = Internal.wrapCurve25519(Internal.curve25519_async);
-      libsignal.Curve.async = Internal.wrapCurve(Internal.Curve.async);
-    };
-
-    Internal.stopWorker = function () {
-      if (Internal.curve25519_async instanceof Curve25519Worker) {
-        var worker = Internal.curve25519_async.worker;
-
-        Internal.curve25519_async = origCurve25519;
-        Internal.Curve.async = Internal.wrapCurve25519(Internal.curve25519_async);
-        libsignal.Curve.async = Internal.wrapCurve(Internal.Curve.async);
-
-        worker.terminate();
-      }
-    };
-
-    libsignal.worker = {
-      startWorker: Internal.startWorker,
-      stopWorker: Internal.stopWorker,
-    };
-
-    function Curve25519Worker(url) {
-      this.jobs = {};
-      this.jobId = 0;
-      this.worker = new Worker(url);
-      this.worker.onmessage = function (e) {
-        var job = this.jobs[e.data.id];
-        if (e.data.error && typeof job.onerror === 'function') {
-          job.onerror(new Error(e.data.error));
-        } else if (typeof job.onsuccess === 'function') {
-          job.onsuccess(e.data.result);
-        }
-        delete this.jobs[e.data.id];
-      }.bind(this);
-    }
-
-    Curve25519Worker.prototype = {
-      constructor: Curve25519Worker,
-      postMessage: function (methodName, args, onsuccess, onerror) {
-        return new Promise(function (resolve, reject) {
-          this.jobs[this.jobId] = { onsuccess: resolve, onerror: reject };
-          this.worker.postMessage({ id: this.jobId, methodName: methodName, args: args });
-          this.jobId++;
-        }.bind(this));
-      },
-      keyPair: function (privKey) {
-        return this.postMessage('keyPair', [privKey]);
-      },
-      sharedSecret: function (pubKey, privKey) {
-        return this.postMessage('sharedSecret', [pubKey, privKey]);
-      },
-      sign: function (privKey, message) {
-        return this.postMessage('sign', [privKey, message]);
-      },
-      verify: function (pubKey, message, sig) {
-        return this.postMessage('verify', [pubKey, message, sig]);
-      }
-    };
-
-  })();
 
   /*
    Copyright 2013 Daniel Wirtz <dcode@dcode.io>
diff --git a/libtextsecure/protocol_wrapper.js b/libtextsecure/protocol_wrapper.js
index 1846f26b9..73391ae4e 100644
--- a/libtextsecure/protocol_wrapper.js
+++ b/libtextsecure/protocol_wrapper.js
@@ -1,11 +1,8 @@
-/* global window, textsecure, SignalProtocolStore, libsignal */
+/* global window, textsecure, SignalProtocolStore */
 
 // eslint-disable-next-line func-names
 (function() {
   window.textsecure = window.textsecure || {};
   window.textsecure.storage = window.textsecure.storage || {};
   textsecure.storage.protocol = new SignalProtocolStore();
-
-  textsecure.startWorker = libsignal.worker.startWorker;
-  textsecure.stopWorker = libsignal.worker.stopWorker;
 })();
diff --git a/ts/components/session/menu/ConversationHeaderMenu.tsx b/ts/components/session/menu/ConversationHeaderMenu.tsx
index caa274622..9dcd0a37e 100644
--- a/ts/components/session/menu/ConversationHeaderMenu.tsx
+++ b/ts/components/session/menu/ConversationHeaderMenu.tsx
@@ -125,6 +125,8 @@ export const ConversationHeaderMenu = (props: PropsConversationHeaderMenu) => {
         isMe,
         isGroup,
         isPublic,
+        left,
+        isKickedFromGroup,
         onDeleteContact,
         window.i18n
       )}
diff --git a/ts/components/session/menu/ConversationListItemContextMenu.tsx b/ts/components/session/menu/ConversationListItemContextMenu.tsx
index f18bb260d..7c3eadfb5 100644
--- a/ts/components/session/menu/ConversationListItemContextMenu.tsx
+++ b/ts/components/session/menu/ConversationListItemContextMenu.tsx
@@ -92,6 +92,8 @@ export const ConversationListItemContextMenu = (
         isMe,
         type === 'group',
         isPublic,
+        left,
+        isKickedFromGroup,
         onDeleteContact,
         window.i18n
       )}
diff --git a/ts/components/session/menu/Menu.tsx b/ts/components/session/menu/Menu.tsx
index 87072aad1..25b83ae7d 100644
--- a/ts/components/session/menu/Menu.tsx
+++ b/ts/components/session/menu/Menu.tsx
@@ -39,9 +39,12 @@ function showCopyId(isPublic: boolean, isGroup: boolean): boolean {
 function showDeleteContact(
   isMe: boolean,
   isGroup: boolean,
-  isPublic: boolean
+  isPublic: boolean,
+  isGroupLeft: boolean,
+  isKickedFromGroup: boolean
 ): boolean {
-  return !isMe && Boolean(!isGroup || isPublic);
+  // you need to have left a closed group first to be able to delete it completely.
+  return (!isMe && !isGroup) || (isGroup && (isGroupLeft || isKickedFromGroup));
 }
 
 function showAddModerators(
@@ -97,10 +100,20 @@ export function getDeleteContactMenuItem(
   isMe: boolean | undefined,
   isGroup: boolean | undefined,
   isPublic: boolean | undefined,
+  isLeft: boolean | undefined,
+  isKickedFromGroup: boolean | undefined,
   action: any,
   i18n: LocalizerType
 ): JSX.Element | null {
-  if (showDeleteContact(Boolean(isMe), Boolean(isGroup), Boolean(isPublic))) {
+  if (
+    showDeleteContact(
+      Boolean(isMe),
+      Boolean(isGroup),
+      Boolean(isPublic),
+      Boolean(isLeft),
+      Boolean(isKickedFromGroup)
+    )
+  ) {
     if (isPublic) {
       return <Item onClick={action}>{i18n('leaveGroup')}</Item>;
     }
diff --git a/ts/util/lint/linter.ts b/ts/util/lint/linter.ts
index 48f5e31b7..e8b939cb7 100644
--- a/ts/util/lint/linter.ts
+++ b/ts/util/lint/linter.ts
@@ -64,7 +64,6 @@ const excludedFiles = [
   '^test/test.js',
 
   // From libsignal-protocol-javascript project
-  '^js/libsignal-protocol-worker.js',
   '^libtextsecure/libsignal-protocol.js',
 
   // Test files