It is possible by choosing the Application via Live Server view and then specifying the depot containing the application, then a deploy job will be created ...
Looking at the Software Tab of the Deploy Job you can see Unistall (instead of Install). This is not possible if you create a Deploy job from the scretch.
So I think that it could be nice to have possibility to choose Install/Unistall starting from the deploy job itself.
open a ticket :)
if the application is one of the standard ones (pkg, rpm, etc) i think when you choose 'uninstall' from the live view you can choose 'standard uninstall commands' or something like that, so you don't need a depot object.