1. Create user command, e.g. Test
2. Set its type to Multi Script
3. Check "Store script in external script file"
4. Enter full pathname to script file
5. Press Save
Result: MC terminates
Now launch MC, go to User Defined commands, select Test command. MC terminates.
So now you have to delete (or maybe rename - i haven't tried) script file.
MC v2.7.2 x64 Portable