You are correct, there's no way for a module owner to do that at the moment, but we are working on implementing that functionality in the website. In the meantime, we can do that for you manually. Email me directly (my first name at mok.com) and let me know the account to deauthorize. Once I confirm the deauthorization is complete, you can let the new owner know that they are free to register under their account.
Thanks for your support and we'll speak again soon via email!
All the best,
Taiho
MOK