If I create Powers, they can not be deleted from the Powers page (it's deleted initially then comes back as a "blank" Power), they can be deleted from the Powers Tab on the Main page.
Look like a bug from the Fantasy Grounds engine. If I can make a workaround for the next version, I will. Although looks like version 2.8 of FGII will fix the underlying bug.
More info here : http://www.fantasygrounds.com/forums/showpost.php?p=108692&postcount=15
Bit worried in how easily I reproduced it (took about 2 mins) but equally I'd not encountered it in my regular play much.
So might be tempted to pass the back on this one, suffice to say it's being addressed in the FGII v2.8 release. Any workaround in the DLR codebase sounds like it may not be simple, or even feasible