how can i delete a single translation entry in my template?

Only the template (“.pot”) file determines what's in there and what isn't. So if you don't need the message, remove it from your template file and upload the new version.

If your project uses Bazaar integration, it's a simple matter of committing and pushing the change to your branch.

are you sure?
i downloaded the .pot template and removed a translation, then uploaded it again.
the translation was still there

also i hope only the project leader or driver can upload the pot template?
or can other people do that aswell?

If this is the template in ZANavi trunk, I only see “address search (online)” and “address search (offline).” Perhaps you looked before the template had actually been imported? Sometimes it takes a while; you can follow progress in your project's translations import queue.

Yes, only the project's owner etc. can upload templates. It's a narrowly restricted capability.

And in the ideal setup, nobody uploads templates: just let Launchpad import them automatically from your bzr branch. This eliminates a lot of human work and all sorts of possibilities for things to go wrong. This will still work even if you don't host your code in Launchpad: just let Launchpad mirror your source tree from elsewhere and we can import the templates (and translations if you like) from the mirrored branch. It will pick up a template file in your source tree, and if you use a recent intltool setup, even rebuild the templates for you. So in an ideal setup, a change to your source code (even in your svn repository elsewhere, for instance) will automatically result in an update of the translatable strings you see in Launchpad.