The first temptation and the quickest answer is, "throw it away!" The second answer is, "pile it in the resource room and someone else can take care of it."
Instead of letting VBS leaders trash everything (curriculum, decorations, extras supplies) or pile it haphazardly in the resource room, a simple solution is to create a recycling center. This makes clean up a breeze and takes the guess work out of what is trash and what is good stuff.
The best place is a hall or spare room near the resource room or storage area. You want to leave the resource room as free of clutter as possible plus you want space to be able to sort and group supplies before storing. Much like you separate paper, glass, and plastic for home recycling, create four areas (piles, boxes, tables, etc.) with the following clearly marked labels: Supplies, Share, Questionable, and Trash.
If needed add a description such as the following to each label:
Supplies - Unused and reusable resources such as markers and paper.
Share - Decorations and curriculum to share with other churches.
Questionable - Anything you are not sure about.
Trash - Hopefully no definition needed here.
Make sure to include recycling instructions as part of worker training. If workers know what is expected ahead of time cleanup becomes easier for both you and them.