Lynn is so right; nothing should be using the 'sa' account. seems like you might be a little new to SQL, and that's why you are using sa for your web site; it's actually a trivial thing to create a new user and assign the permissions to the database your website will use.
locking the user 'sa' out of the ability to use management tools would most likely effectively lock YOU out of the database as well.
do you need a GUI or script example on how to create a login and a user, and then assign permissions?
Lowell