code: public void removeMember(User user) {
          long userId = user.getId();
          members.remove(userId);
          nicknames.remove(userId);
          selfMuted.remove(userId);
          selfDeafened.remove(userId);
          muted.remove(userId);
          deafened.remove(userId);
          getRoles().forEach(role -> ((RoleImpl) role).removeUserFromCache(user));
          joinedAtTimestamps.remove(userId);
      }
docs: Removes a member from the server.
  
  @param user The user to remove.