Agree that it's really misleading. Even on a recent version of Jenkins, it says "Delete Repository" on both the context menu and on the detail page for the job itself. I think "Delete Pipeline" would also work and is a bit briefer.
I agree, the current wording sounds like it's going to delete your git repository. Yikes!
If it's going to delete the Jenkins Pipeline, why not just call it "Pipeline" in the menu?