Removes a role from a user.
@Action(
  id = "user_remove_role_action",
  label = @Translation("Remove a role from the selected users"),
  type = "user"
)
Expanded class hierarchy of RemoveRoleUser
class RemoveRoleUser extends ChangeUserRoleBase {
  /**
   * {@inheritdoc}
   */
  public function execute($account = NULL) {
    $rid = $this->configuration['rid'];
    // Skip removing the role from the user if they already don't have it.
    if ($account !== FALSE && $account
      ->hasRole($rid)) {
      // For efficiency manually save the original account before applying
      // any changes.
      $account->original = clone $account;
      $account
        ->removeRole($rid);
      $account
        ->save();
    }
  }
}