Barry Irby
Do you have an Oscillating tool? MultiTool or whatever they call it?
You can slide the blade under the top between it and the cabinet and cut the glue. Would not surprise me to find it is only glued and a few places. (Except for Murphy's Law)

Start at a corner. Drive a thin wooden wedge in or even a putty knife. A sheet rock knife might work well, tough and thin.