How can one safely remove a non factory set radio from a 1996 Ford F350 disel?

How can one safely remove a non factory set radio from a 1996 Ford F350 disel?

Added (1). This is not the same radio that came in factory stock.

Replacing radios isn't complicated. There are four small holes in the frame of the radio. You place a piece of stiff wire bent in a "U" shape with each end in one of the holes on both sides of the existing radio, push in on both sides to release it. Slide it out then disconnect the antenna lead, the power lead and the speaker wires. Always a good idea to disconnect the negative battery clamp before you start to eliminate possibility of shorts.