HELP !! Remove php

This code does not delete the user when clicking on the button!

public function frmExclUser () {}
$ user = new user ();
$ arrayUser = $ user-> delete ("and cod_usu = & # 39; {$ _ REQUEST['cod_usu']} & # 39; ");

There is a delete button referring to frmExclUser but it does not work, any help is valid