Repo privacy when transferring site to client

Continuing from the above thread, I have a followup question

I want to transfer the site to client so they handle the netlify payment and hosting etc. how ever I do not want to give them the access to my GitHub account or theme. How can I make sure that I can transfer the website which will work as normal but client will not have access to my GitHub account or the repo etc. as the source code was not part of the web development.

it is a Hugo theme website thanks

The repo is not transferred as that’s not stored on Netlify.