Scratch Disk Errors

The real problem I'm trying to solve is "scratch disk". Adobe won't let me run Photoshop because my scratch disk is full. Storage showed 3.5 gb available. Scratch disk shows 3.5GB available. I want to get it to at least 20gb free. I finally got storage to show 37gb free but Adobe error still shows my scratch disk at 3.5gb free. How do I get Scratch disk freed up if removing files doesn't move the needle?