How to disable a specific page for a specific user

There is a global variable containing the current page in the admin area, called $pagenow. You can use this to detect where the user is now.

Now, in your case, you are on admin.php and there are 3 parameters set in the URL, page, delete and id. So:

if( 
    in_array( $pagenow, array('admin.php') ) &&
    ( $_GET['page'] == 'wpProQuiz' && $_GET['action'] == 'delete' && $_GET['id'] == '1' ) 
) {
    // Now check the current user
    $user = wp_get_current_user();
    if ( $user->user_login == 'remo' ) {
        wp_safe_redirect( admin_url() );
        exit();
    }
}

This will redirect the user back to their dashboard. Not that you don’t need to check the password, since the username is unique.