Licence cancelling on PC

I have reached the 5 numbers of PCs permitted.
How can I dis activate the licence on an old PC to transfer to a new one?
Many thanks for keeping me in the loop

Activate the licence on a new device then uninstall CCleaner from a device where it is no longer needed.

Or do it the other way round, either way it’s not a problem.

People do want to move their licences from an old machine to a new one, so you are allowed to exeed your allowance for a short while.