Red remove button should not be visible on required elements. See screenshot.
Fixed in git plugin 2.5.1 and later
not specific 2.x but annoying ...
Looks like an issue with the Git Plugin. On 1.x, it simply has "Delete Repository" buttons that do the same.
For comparison, Subversion Plugin removes that button when there's only one location, and Jenkins 2.0 handles this correctly.
Daniel will investigate.
I think this is also the behavior from 1.x, as it's a list of repositories. See: