Thanks Robert,
Looking at the RemoveRegistry table in Direct Editor, you would add a new item, set the root to -1 if it's a local machine setting, then the Key field to the key you want removed and the Registry value name.
I believe the component reference could be RegistryData_Machine for HKEY_Local data.
The table actually has a dropdown with a handfull of choices for that field.
Worse case scenario is you might have to try them out to see which one works for the key you are removing.
Otherwise the other fields are kind of self explanantory.
The only remaining question is whether or not it will remove and entire key structure. I will be testing that part out when I have more time to play with it.