There's /remote off, but afaik no way to "lock" this state, and no way to deny access to (changes of) remote scripts. Could make up a feature suggestion.
With a dll, you can hide, or even close the script editor if you want. You can also know if it is opened or closed, but really, do this in order to prevent user to edit your code isn't a good idea.
#mircscripting @ irc.swiftirc.net == the best mIRC help channel
OK.. I now know that it can be done, although I like my scripts to be able to be viewed/edited by others so that they can (hopefully) learn from my own experience.