function removeUser($userNameRemove)
{
    $mysession = new Session();
    $mysession->initSession();
    $wallRepo = new WallRepositoryService();
    $userRepo = new UserRepositoryService();
    $userName = $_SESSION['usuario'];
    $wallId = $wallRepo->getWallIdByUserName($userName);
    $userIdRemove = $userRepo->getUserIdByName($userNameRemove);
    $results = $wallRepo->removeUser($userIdRemove, $wallId);
    if ($results === TRUE) {
        $response['valid'] = true;
    } else {
        $response['errorMsg'] = "Lo sentimos, hubo un error al eliminar el usuario de su lista.";
        $response['valid'] = false;
    }
    echo json_encode($response);
}
<?php

require_once dirname(__DIR__) . "/services/UserRepositoryService.php";
$userRepo = new UserRepositoryService();
$userName = $_POST['userName'];
$result = $userRepo->verifyUser($userName);
if ($result == null) {
    $response['errorMsg'] = "Lo sentimos, el usuario ingresado no existe.";
    $response['valid'] = false;
} else {
    $response['valid'] = true;
}
echo json_encode($response);
<?php

require_once dirname(__DIR__) . "/services/WallRepositoryService.php";
require_once dirname(__DIR__) . "/services/UserRepositoryService.php";
$wallRepo = new WallRepositoryService();
$userRepo = new UserRepositoryService();
$userId = $_SESSION['id'];
$wallId = $userRepo->getWallIdById($userId);
//$privacity = isset($_POST['change']) ? $_POST['change'] : $wallRepo -> getPrivacityById($wallId);
$privacity = $wallRepo->getPrivacityById($wallId);
$checkedPrivate = "";
$checkedSemiPrivate = "";
$checkedNormal = "";
$checkedSemiPublic = "";
$checkedPublic = "";
$usersPrivate = null;
$usersSemiPrivate = null;
switch ($privacity) {
    case 'privado':
        $checkedPrivate = "checked";
        $usersPrivate = $wallRepo->getUsersById($wallId);
        break;
    case 'semiprivado':
        $checkedSemiPrivate = "checked";
        $usersSemiPrivate = $wallRepo->getUsersById($wallId);
        break;
    case 'normal':
        $checkedNormal = "checked";
        break;
    case 'semipublico':
        $checkedSemiPublic = "checked";
<?php

require_once dirname(__DIR__) . "/services/WallRepositoryService.php";
require_once dirname(__DIR__) . "/services/UserRepositoryService.php";
require_once dirname(__DIR__) . "/domain/Session.php";
$mysession = new Session();
$mysession->initSession();
$wallRepo = new WallRepositoryService();
$userRepo = new UserRepositoryService();
$json = $_POST['data'];
$data = json_decode($json, true);
$newData['privacity'] = $data['opt'];
if (isset($_SESSION['usuario']) and preg_match("/^[a-zA-ZñÑáéíóÁÉÍÓÚ]*\$/", $_SESSION['usuario'])) {
    $userName = $_SESSION['usuario'];
    $newData['wallId'] = $wallRepo->getWallIdByUserName($userName);
    if ($data['opt'] == 'private') {
        //Obtengo el userId de cada userName
        $newUsers = array();
        foreach ($data['users'] as $user) {
            $newUsers[] = $userRepo->getUserIdByName($user);
        }
        $newData['users'] = $newUsers;
    } else {
        if ($data['opt'] == 'semiprivate') {
            //Obtengo el userId de cada userName
            $newUsers = array();
            foreach ($data['users'] as $user) {
                $newUsers[] = $userRepo->getUserIdByName($user);
            }
            $newData['users'] = $newUsers;
        }