How to disable specific message displayed by contrib/core?
Once a user has been deleted, The User relationships module have to delete all relationships associated to deleted user but it doesn't work correctly. I implemented hook_user_delete() in a custom module and delete non-approved relationships associated to the deleted user. like this:

/**
 * Implements hook_user_delete().
 */

function YOUR_MODULE_NAME_user_delete($account) {
  //user_relationships_delete_relationship($relationship, $user);
  db_delete('user_relationships')-&gt;condition('approved', 0 , '=')-&gt;condition(db_or()-&gt;condition('requester_id', $account-&gt;uid)-&gt;condition('requestee_id', $account-&gt;uid))-&gt;execute();
}