When you connect to a 'print server' and open the Sharing tab on a printer's Properties, you are unable to remove an alternate driver by clearing the check box from the Additional Drivers area.
This behavior is by design, as you can only add alternate print drivers using this method.
To remove alternate printer drivers from a 'print server':
1. Start / Run / \\
2. Open the Printers folder.
3. On the File menu, press Server Properties.
4. Select the Drivers tab.
You can Add, Remove, Update, or view driver Properties.