I cancelled a Mobile Sync due to having lots of unwanted groups in the Global Inbox I did not realise. Following this I was left with 2 groups on the iPhone which were not in the DT on the Mac Global Inbox. So i could not delete them!
So what I did was edit them on the phone, such as adding a Flag, re-synching, then this re-created them on DT on the Mac, so I could then delete the groups, then re-sync and they are gone from the phone.
Just wanted to provide feedback on this issue and how I fixed it.