I had a guitar come into the shop for a complete overhaul
and needed to remove the pickguard.
The trick is to remove the pickguard
without destroying the soundboard, pickguard or existing finish.
Here is a quick tip that allows you to do this.
I use Naptha to release the adhesive that attaches the pickguard to the soundboard.
Naptha is a distilled petroleum by product
and is used to make common products like charcoal lighter fluid and camping stove fuel
as well as some cleaning products.
It will not destroy the finish or pickguard material.
I begin by rubbing a small amount on the edge of the pickguard using a cotton ball.
You can use a small exacto blade to lift an edge of the pickguard if needed
so the naptha can begin to work itself under the pickguard.
As the adhesive begins to release you can use a spatula to help the process along.
Be careful not to damage the pickguard or soundboard.
After a few minutes the pickguard will release.
Clean up any adhesive residue with more naptha and continue with the repair.