Vanilla 1.1.9 is a product of Lussumo. More Information: Documentation, Community Support.
1 to 8 of 8
The SE2.0 philosophy (as I understand it) is that whatever was posted onto the database stays there pretty much forever, I don't recall seeing a post that was truly obliterated from the database on math.SE.
If the SE1.x software used on MO has the same philosophy (which I suppose it has) then it's pretty hard to remove something from the database completely.
In one case here is what I did: Edited the unwanted answer down to "(Duplicate)" or something like that. Of course I had to undelete it to do that, then delete it again afterward.
We (moderators) can't completely remove the answer either, but it really isn't a big deal to just leave it as is. Most people can't see it, and for those who can (you and 10k+ users), it's unobtrusive (at the bottom of the page and colored "deleted").