How to delete backup file after upgrade of branch on Launchpad?

Launchpad's code hosting is provided over SFTP (as well as other protocols), so you can use an sftp client (such as sftp or lftp) to manipulate branch files directly. You can also use lp:hitchhiker, which supports all protocols supported by Bazaar itself.

If you use hitchhiker, you can do something like:

$ ./hitchhiker lp:launchpad rmtree bzr.backup

changing lp:launchpad to your branch's location. More info on how to use hitchhiker can be found in the README.txt file in the root of the hitchhiker branch, or by running "hitchhiker . help".