Cadillac Repair: 1995 cadillac sls seville, cadillac sls, brake caliper

Question
Is there a simple and easy way to unlock a brake caliper? its only locked on one wheel i haven't really looked at it but all my wheels will turn when in drive but my left rear will will not turn it just slides across the ground except when i put it in reverse then it can go backwards.  Can someone please help me? Thanks for everything!

Answer
Apparently the caliper is frozen (stuck on the brake rotor due to a defective brake piston.

About the only way to get it oFF is to remove the 2 large pin bolts on the top and bottom of the caliper and pry the caliper off the rotor and replace the caliper.

NOTE: ALWAYS replace calipers in sets. In other words replace BOTH rear calipers as the other side will soon do the same thing.