I added a Bus Terminal to my city (the big kind). Later in the game, I noticed it basically disappeared leaving just a trail road and a small garage.
Annoyed, I decided to delete it and rebuild one. Except that deleting it only removed the small garage left. The small dirt road remained. I cannot delete it or build anything over it.
I tried to delete the main road next to it (hoping it will ask me if I want to delete the building too), but it didn't ask anything. Now I can't even rebuild the old roads because it says it cannot intersect the dirt road. I can't build over it for the same reason.
Clicking to bulldoze doesn't do anything.
Best Answer
It's a bug that is not fixable short of the devs releasing a patch. However you could attempt to fix this via natural disaster. Unfortunately/fortunately natural disasters don't destroy roads. However, if perhaps the game sees these roads in particular as part of a building (since they were used to upgrade one) then perhaps it will make an exception. I recommend unleashing a earth quake or comet on it and seeing what happens.