Renaming Theme: General regulation?

Hi guys,

I want to purchase a theme to build a website for my client. So, I don’t want my client or other people to see on which Theme the design is based. The themes code is licensed under GPL.

Now I am wondering if it is allowed in general to rename the theme so that it shows in WordPress Backand another name and if it is allowed to remove the data (theme name) in the styles.css?

Do I have to ask for permission or is there a general regulation in that case?

Thank you for your help!

Greetings,
Linda

[Moderator Note: No bumping. If it’s that urgent, please consider hiring someone instead.]