Can I cancel a book that is on a WL hold with an inactive member?  I no longer want to send the book out, I already went to the PO with other books while this one sits with an inactive member.  

No, as long as a book is on a WL hold it cannot be cancelled, it will roll to the next person at 48hrs so if you don't want it to do that, put your Bookshelf on Vacation Hold and when the 48 hrs expires the book will go onto your Bookshelf and  you can remove it and then take the Vacation Hold off.

Unfortunately, once a book goes on a member's WL hold, it's stuck with that person until it times out after the 48 hours.  Your best bet is to put your shelf on vacation hold before the book rolls over to the next wisher.  Then, while your shelf is on hold, you can go and delete the book.  That will stop it from rolling over to the next wisher, at least.

Vacation hold worked, thanks!