Cannot delete computer groups

I have a main WSUS 3.0 SP2 server and 5 downstream replica servers.

I am trying to consolidate computer groups but cannot delete them. The
option is there but when i try i just receive the egg-timer and after a
short while it closes the console. The groups i have tried now show as
grey..

The groups had no computers in them and gpo targeted the computers to the
new groups..

Any help would be appreciated