Found a solution - I had to delete it from the registry.

First I found the windows messaging subsystem key -
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles
looked for the subkey that expands - it has a folder under it for each account in the profile.

To find the correct one to delete I selected each and double clicked on the Account Name value which then showed the ascii conversion of the hex value.
Found the " - Outlook 2010" account which had so many values missing and deleted it.
Funny thing was it was the account numbered 000000013 - unlucky for me

Once deleted I ran Outlook and the account was gone and I could then delete the data file with no problem.