Registering my account to a new machine.

I was recently locked out of premiere pro app on my older windows7 machine. The onscreen reason was "billing error" but i found out it was my machine was no longer supported. Ive now got a windows10 machine that already has premiere pro downloaded (registered to someone else). How do I re-register this machine and software to me and restart billing and editing? Or is it easier to download the whole suite again and activate to myself (would I have to delete the existing apps and start again).