Вот так:
add_action( ‘init’, ‘blockusers_init’ );
function blockusers_init() {
if ( is_admin() && !current_user_can( ‘editor’ ) && !current_user_can( ‘administrator’ ) &&
! ( defined( ‘DOING_AJAX’ ) && DOING_AJAX ) ) {
wp_redirect( home_url() );
exit;
}
}