I don't use Zoho Mail and I want to close my free account(s)

I don't use Zoho Mail and I want to close my free account(s)

It is absolutely ridiculous how problematic it is to try to close a free account.  We have, over time, evidentially opened more than one trial account.  Now we are actually trying to open an account to run our business on Zoho and it won't let me use an email address from our own domain because it had been used months ago. All I want to do is close EVERYTHING and start over.  I am getting so aggravated I am about to go to a different service.