Windows 8.1 issues (didn't know it didn't work with this OS)

Having problems with slow computer, so I got Grime Fighter, as I have really liked the other programs I have. I do have Windows 8.1, but didn’t realize the software didn’t work on Windows 8.1 (should have seen something about this as I was purchasing, but we won’t go there.) 1.) Will this product work with Windows 10 (as soon as it is up and running)? 2.) Assuming it will work, how can I uninstall the program until that time so it doesn’t just start itself?

GrimeFighter does work with Windows 8.1
Yes, it will work with Windows 10 as well. (basically it already does, but Windows 10 is not yet released)

To remove it:
control panel > software > avast > change