This article is from the Food Preserving FAQ, by Eric Decker email@example.com with numerous contributions by others.
From: firstname.lastname@example.org (Paul F. Levine)
Getting fruit leather off of the dehydrator tray
I was having a little trouble getting my fruit leathers off the American
Harvester solid sheet trays even when they were really dry. The booklet that
came with the dehydrator said to try to peel it off while it was still warm.
Not so I find. This is what seems to work well:
Once the leather is really dry (around 24 hours +or-) take the sheet right
from the dehydrator an put it into the refrigerator for only about 5 minutes
(too much more and the leather begins to rehydrate). Then the leather comes
off of the sheet.