I debugged in a tank drone to see how well I fared.
It seems that they are easy to kill if you have the following:
Apost-threshold mutant character. (So it isn’t hostile until you attack.)
Rivtech short shotgun, loaded with explosive rounds. (The explosion makes it moderately injured with one hit, even though the bullets don’ pierce it’s armor.)
Good armor, for when it fights back. (In my case it was heavy survivor armor)
EDIT: Did the same, but inside my vehicle.
I had curtains installed in my vehicle, and closed them. This way, the tank drone doesn’t go “OMG A THING IS DRIVING IN A VEHICLE MUST KILL” (Wing mirrors provide excellent vision.)
The tank drone died before all the turrets were finished firing.