starter on 1990 Cadillac DeVille

when trying to start the car and you let off the key the starter keeps on running until you disconnect the battery.

Asked by for the 1990 Cadillac DeVille
Starter may be shorted internally, starter relay sticking or ignition switch problem.
2 more answers
Have the ignition switch, wiring and starter checked out. Could be any of them.
the bendix is sticking on the starter.