Just wont come off on my '17 C-Force 500HO!! I dont want to break it but I just cannot get it off!!

Undo the inner clamp just outside the air-box, you can slide the air-filter and adapter barrel together.
There is a lip on the barrel that can feel tight, You may find it easier to remove the first time as a pair and get a feel for it

Have you found a replacement filter? I jave a 2016 500 HO EPS and have been searching for one?

yes, uni filter works with the 500 ho eps