Question about reinstalling Adobe ID into a new computer

First, you need to find out how the software was registered with Adobe. I'm assuming the account was not a Teams account.

If the person who left had it under their name, then the subscription actually belongs to them, regardless of who is paying for it. If it was under their name, contact Adobe* and your credit card company and stop payments on the account. 

*If you have the password, you can change the credit card info on the account and/or cancel the plan.

If it isn't under their name but under a supervisor's name, log into the account and change the password. When you install the Creative Cloud app, use the new password and remove the other persons activation if necessary.

This question was different enough from the original location that I moved it to a post of its own.

Install it with the CC Application. You can dectivate the copy from the other cmputer to get the free license now. If the other one is still using the licence, change the password.