removeUser method
called when a user stops sharing his location
Implementation
void removeUser(String? atsign) {
if ((atsignsToTrack != null) && (hybridUsersList.isNotEmpty)) {
hybridUsersList.removeWhere(
(element) => compareAtSign(element!.displayName!, atsign!));
if (!_atHybridUsersController.isClosed) {
_atHybridUsersController.add(hybridUsersList);
}
}
}