You can use a plugin such as KvConfigs (
https://forums.alliedmods.net/showthread.php?p=2018273) to force cvars to remain at a certain value and prevent any changes, although all you really have to do is remove the lower bounds on the cvar and set it to 0 afterwards.
Zeddy, this version is completely map dependent, if the map doesn't have any logic to make the dividing wall fall then the wall isn't going to fall. There is a cvar that you can set to the number of seconds it takes the wall to fall (see second post), but it doesn't have the logic to force the wall down.