This is a guess, because I'm not familiar with the 93 500E, but if it has 2 pistons, one on each side of the caliper, the inner one is probably siezed in the bore. If it has only 1 piston (or pistons) on 1 side of the caliper, it should 'float' (move in and out) when the brakes are applied so that equalizes the pressure on both sides of the rotor. In this case, it sounds like the slides (the cylinders running over the caliper mounting bolts) are siezed.

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1986 560SL
2002 Toyota Camry
1993 Lexus