PHP script not workin

WE have a 3rd party module that needs PHP script to customize the upload of a stock update.

Like the file we get it has SKU name with space “-” and “/”. But the SKU in MAgento do not.

So i created a script that removes “/” and “-” and another script that trims the cell.

Each script works sepretly but not together. Anyone that can help me with what is wrong?

<?php
 /* Your custom script */
return str_replace(['/','-','.',','],'', $self);
return trim($cell [0]);