Leaving for Disney in a few days. Should I log on to the Disney site and cancel the Fastpasses that my touring plans didn’t use?
So, you would book other FPs, right? You always, always, always use at least three FPs!
I would keep them for several reasons. First, park conditions can change and the currently “unnecessary” FPPs may turn out to be valuable on the day. Second, if you cancel them then those opportunities are considered used, but if you keep them then you can go on MDE and swap them for other available FPP.
The only reason I can think of for canceling FPPs is to get around tiering and/or the one FPP per attraction restriction by being able to get the unrestricted 4th FPP at a kiosk earlier. However, you are hoping that FPPs for the desired attraction will still be available at that point