If a configuration variable is locked at an upper level, E.G. Site, using %lock
And one needs to un-lock it at a lower level to reset it for a specific project "HOW" There isn't an %unlock and %undef does not work either.
Just FYI if anyone else stumbles upon this thread the solution I found was to make hidden files and folders visible. Give myself admin privileges to C:\ProgramData\Bentley then search the Bentley folder for *.cfg files. I looked though the .cfg files until i found one called capabilities and locks. Opened to edit and added a plus to the variable i wanted to change and it worked. If you want to unlock a variable for editing in MS i think you can delete the %lock from the front of it but i would be very careful you dont mess up the syntax. Good luck!