This operation may require quite a bit of strength. Disassemble the rotor with a rocking motion as if trying to break it and at the same time pulling the ends out. Usually occurs if you tried 2 magnets on a rotor first. The rotor will not start spinning on its own. Give it a slight push.
Rotor is jammed.
Find the exact cause and fix the problem. This may require breaking off the stands and reattaching them to the board. You may try to lubricate the axles with WD-40 or any other lubricant. Electromagnet attracts the magnets instead of repelling them. Switch the electromagnet wires.