There's an option in 'input' section of in-game ENB config to select 'no key' for any of the functions, which will set the key to 0 (zero) in enblocal.ini. If editing the file manually, I'd also set it to zero just for consistency, e.g.
[INPUT]
//shift
KeyCombination=16
//f12
KeyUseEffect=0
//home
KeyFPSLimit=0
//num / 106
KeyShowFPS=107
//print screen
KeyScreenshot=44
//enter
KeyEditor=13
//f4
KeyFreeVRAM=0
KeyBruteForce=0