Any way to remove these messages?

[Kemi]

I am wondering if there was a way you could remove the Cheats are not enabled on this server message or the Unknown command <cmd> message.
Any ideas? I know you can change the connected message and maybe the disconnected but not sure about the ones I mentioned...

[Ni3ls]

Check localized strings. Leave that string empty

[IzNoGoD]

Catch them in the callback_playercommand, then dont execute them

[maxdamage99]

Someone wants to steal)

[Kemi]

Someone wants to steal)

What do you mean???