Hi Tynesider,
You should be more patient with your question. Sometimes it'll takes a while for somebody to answer.
While in your Social Hub, press the Menu button, tap on the [Accounts and sync], tap on the account you want to remove and select [Remove account].
Hi, That doesnt work, try it.
I found out that it cannot be removed and the only way is a reset of the phone.
I've sent my SG2 back to o2 and I'm back on payg with my old phone now, there are too many things this phone doesnt do compared to the ipone that I wanted. Good for some but not for me.
Thanks
So, I have been looking for the same thing, as I just wanted to use the gmail app for my gmail and not the social hub. While playing around with my phone I figured out how to delete the email without having to reset my phone

Process:
1) Open the account and go into the inbox in Social Hub.
2) Push the Name of the account (In my case it was in the top left corner called "Gmail")
3) Choose the menu button on the bottom left of the phone (SII)
4) Choose "Delete Account"
5) Place a check mark next to the account(s) you want to delete.
6) hit the delete button.
All done and I can still get my emails thorugh the Gmail app native to Android.
Profit?
TheWhite