Can remove a member from a group

lib/helpers/groups_helper.dart

@@ -297,6 +297,15 @@ class GroupsHelper {
           .addBool("accept", accept)
           .execWithThrow();
 
+  /// Remove a member from a group
+  ///
+  /// Throws an exception in case of failure
+  static Future<void> removeMemberFromGroup(int groupID, int userID) async =>
+      APIRequest.withLogin("groups/delete_member")
+          .addInt("groupID", groupID)
+          .addInt("userID", userID)
+          .execWithThrow();
+
   /// Turn an API entry into a group object
   Group _getGroupFromAPI(Map<String, dynamic> map) {
     return Group(

lib/ui/screens/group_members_screen.dart

@@ -146,6 +146,8 @@ class _GroupMembershipTile extends StatefulWidget {
   __GroupMembershipTileState createState() => __GroupMembershipTileState();
 }
 
+enum _MemberMenuOptions { DELETE }
+
 class __GroupMembershipTileState extends State<_GroupMembershipTile> {
   int get groupID => widget.membership.groupID;
 
@@ -168,13 +170,9 @@ class __GroupMembershipTileState extends State<_GroupMembershipTile> {
   Widget _buildTrailing() {
     switch (widget.membership.level) {
       case GroupMembershipLevel.ADMINISTRATOR:
-        // TODO: Handle this case.
-        break;
       case GroupMembershipLevel.MODERATOR:
-        // TODO: Handle this case.
-        break;
       case GroupMembershipLevel.MEMBER:
-        // TODO: Handle this case.
+        return _buildMemberCase();
         break;
 
       case GroupMembershipLevel.INVITED:
@@ -193,6 +191,43 @@ class __GroupMembershipTileState extends State<_GroupMembershipTile> {
     return null;
   }
 
+  Widget _buildMemberCase() {
+    return PopupMenuButton<_MemberMenuOptions>(
+      itemBuilder: (c) => [
+        // Remove membership
+        PopupMenuItem(
+          child: Text(tr("Remove")),
+          value: _MemberMenuOptions.DELETE,
+        ),
+      ],
+      onSelected: _handleMenu,
+    );
+  }
+
+  void _handleMenu(_MemberMenuOptions value) {
+    switch (value) {
+      case _MemberMenuOptions.DELETE:
+        _removeMembership();
+        break;
+    }
+  }
+
+  void _removeMembership() async {
+    try {
+      if (!await showConfirmDialog(
+          context: context,
+          message: tr("Do you really want to remove this membership ?")))
+        return;
+
+      await GroupsHelper.removeMemberFromGroup(groupID, userID);
+    } catch (e, s) {
+      print("Could not remove membership! $e\n$s");
+      showSimpleSnack(context, tr("Could not remove this membership!"));
+    }
+
+    widget.onUpdated();
+  }
+
   Widget _buildInvitedCase() {
     return MaterialButton(
       onPressed: _cancelMembership,