Currently there is no provision to delete Revisions except through the database where they are stored. I can’t tell you off the top of my head, which table sorry. Additionally, there is no way to delete all revisions.
That said, I think it is a great new feature idea to add a little delete icon or ‘x’ next to each revision to delete the record.
I do like this and will look into adding this to the features pipeline for the next release.