It is possible to destroy your own quarters. Is that a bug or could it be tactical. I.e if you have many quarters with little value and are not winning you can destroy a lower valued quarter to build a quarter that has a higher value during your next turn.

No, this isn't a bug, you can indeed destroy your own quarters.
This can actually be a strategical decision in certain cases.

In several extensions, there exist cursed buildings, abilities to block a slot in other's cities with an useless building, or buildings providing a great one shot power upon construction but with a payback afterwards. With that kind of buildings it becomes more interesting to play the warlord on yourself.
I still hope one day to bring such extensions in the playroom.

Thanks and sounds interesting. I did not know this game until it came to the PR but it is a good one.