I think you need a special removal tool to get out the stereo OR:
Bend two 9 or 10 inch sections of coat hanger into a handle\half-moon\180 degree turn shape. Something like this: > or this ]
On each side of the stereo should be 2 holes, one on top, one on the bottom. slide each coat hanger into the 2 holes of one side and push... you'll feel a click. The hangers should have released the locking mechanism on each side. Keep the hangers in the holes and pull out the stereo.
This should work....

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