How to remove a Caster photos
You'll need 1 of these 3 tools
Upper left-Pry bar
Upper right-Handy bar
Bottom-CURVED wire cutter but not as good as the others
After working the tool lifting edge under the caster, pull down to create leverage to lift caster upwards.
Add shims as or if needed until caster is out of base.
One drop of oil where the caster stem is in the base is very helpful.
Above all, do not use a SCREWDRIVER