Remove dev release

At the moment I've have a 7.x-1.x dev branch of taxonomy menu with a corresponding -dev release, http://drupal.org/node/794334. I want to have a branch for my 7.x dev called '7.x.'

I've made the branch in git but I'm unable to create a new dev release on d.o or delete the old 7.x-1.x branch on the git origin. I was wondering you guys could help me out with that. Thanks a lot!