I'm not positive about this, but you could take a look at your smbpasswd file in /etc/samba. You will see lines that look like this:
spress:5028:0AB2EE2B244A85F0AAD3B435B51404EE::...
maple$:5044:36DA8ECD41D327D6AAD3B435B51404EE:...
tbc007$:5045:9F4644892058E928AAD3B435B51404EE:...
jhummer:5047:C23413A8A1E7665FAAD3B435B51404EE::...
lshellenberg:5048:C23413A8A1E7665FAAD3B435B51404EE:...
The line you need to concern yourself with is obviously the computer name, ie in my case for example 'maple$'.
I think you could probably just delete the line referencing the computer name. I would make sure to backup the smbpasswd file BEFORE doing this - just in case this causes a problem.
Good luck!
Regards,
Patrick