Try penetrating fluid. Let it soak over night.
If the bolts are out and the piston in the caliper is locked up, try loosening the brake line hose. If the hose has collapsed internally it would hold back the brake fluid flow, and the hose also would need to be replaced. Otherwise you just pry it off. If that don't work then take out the 2 bolts holding the brake caliper bracket out, and take the caliper and rotor off all at once.
When the torch fails, I use explosives. It may be time to blast!
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