Red remove button should not be visible on required elements. See screenshot.
I think this is also the behavior from 1.x, as it's a list of repositories. See:
Daniel will investigate.
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.
not specific 2.x but annoying ...
Fixed in git plugin 2.5.1 and later