If you have the script itself, just go through all the files and find the functions that are responsible for it, most likely they should go to a remote server, if so, you can either delete it altogether, or send it already to your server where you fudge the desired response.
And how to delete specifically you, it is difficult, I do not know, what you have there for a script and how it is protected.
But as I understand it, there is something like a serial number or login password to envato or something like that?