In your case it's easy: log into Software Center, click the tab with the three cogs on it and click the button which says 'deactivate all'. In my case the machine was already sold before I thought of deactivating the software, and the fact there doesn't seem to be a method for me to centrally manage my activations is ludicrous.
I've also quickly learned that it's pointless asking off-the-wall questions on here. It's a sparsely-populated users' community contributed to by peers, and while I have had some help with a couple of 'newby' queries when I first got started, if no one's had the same problem as you, you won't get an answer. Originally, I stupidly thought it would be periodically visited by an Arturia product specialist, capable of answering pretty much anything. But it isn't.
