Best practice generally if you dont want people to change your printer settings is to have the Everyone security group set as per the image i've attached. This will allow them to cancel jobs etc if required, and they will be able to print in colour if needed, but will have to change that setting each time they want to print, as the change wont be saved to the server.
If that's too much hassle for the users (and i know it can be for some) then you could always install and share 2 instances of the printer, 1 printer set with colour settings and the other with B&W.