I'm not saying I'm in the "best of us" category, but that's definitely happened to me before (multiple times) and I recall wishing each time exactly what OP is suggesting, a way to cancel reports.  While it's not critical, it would be a good feature to have especially if it wouldn't take much effort to implement--and I don't know exactly what it would take, but I'm assuming it wouldn't be a big deal for Theymos to do.

Yep, I do remember this being brought up before.  But as with most suggestions, it was discussed and then nothing was done about it.