Warships absolutely have a “self destruct button” it’s called scuttling. Done to deny the enemy the capture of the ships, or to lodge a wreck in an important location, so it blocks passage. Usually a “self destruct” is ships scuttling, but for space - you can’t really do anything to a spaceship to “disable” it and prevent it from ever being used, unless you blow it to bits. Also, explosions are cool.

Same thing for abandonned tanks - burning those is often done - especially if you just lost a track, and the tank is fully operational but cannot move. If you have no chance of retrieving the vehicle, it’s better to burn it than to deny the enemy the knowledge about its system, weakpoints, comms etc.