I've forked a repo on Bitbucket, it was a mistake, I want to delete the fork.
Rather than go through the hassle of merging it back in (which would be misleading as I haven't made any changes, anyway) I'd just like to delete it.
I can't see a front-end option in Bitbucket for this, but there must be one... right?
Considering that a BitBucket fork simply create a repo on the BitBucket side, the simplest way to delete said fork is... simply delete the BitBucket repository.
(Update May 2014)
See Deleting a Bitbucket Repository:
Example: