Add "delete user roles" method

[pwildenhain]

As of today, the "User roles" methods seems a little wonky, especially when creating a brand new role. So we're going to hold off on creating these for now, and wait to see if:

1. Wonky behavior stops
2. Anyone really wants this in the first place

[pwildenhain]

If you want to follow along with what the REDCap admins think about this: https://community.projectredcap.org/questions/125602/what-are-the-minimum-field-requirements-for-creati.html