First of all, don't remove any FAdmin files. DarkRP depends on them, don't be an idiot. Do it right.
How to do it
1. Go to darkrp/gamemode/modules 2. make a file called sh_removeFAdmin.lua (make sure it isn't secretly sh_removeFAdmin.lua.txt, make sure "show file extensions" is turned on) 3. Paste the following code in it:
timer.Simple(0, function() FAdmin.GlobalSetting.FAdmin = false end)
4. restart server or change level.