I activated WHMCS on my VPS - oops!

Sooo, I went to Install cPAddons Site Software and installed WHMCS on my Cloud VPS. Now it's available on all clients cPanel. Two questions: Is there a way to not make it available to everyone and just specific users? AND, On one of my test domains I went ahead and clicked "Buy License" and it recognized my e-mail address (how'd that happen), showed that charges were going to be prorated, but the BIG Checkout button in the top right corner wasn't clickable. I backed out. :eek: Then I received an email from "cPanel Ticket System account creation" wanting me to "Please set your password here:" with a link which I have yet to get the courage up to click. So, I'm interested in utilizing WHMCS, just not on that particular domain; so not sure how to proceed and what trouble I've gotten myself into. Can someone HELP!