lol thats so evil but not the less true.
You need to recode the client or better you need to recode client and server to make it secure. Just recoding client is pretty useless since a player that want to hack can just use a non edited client and connect to your server and use the console.
So you basically need to do 3 things.
1) You need to disable the commands on client
2) You need to disable commands on server or change them to custom made commands
3) You need to recode the packet protocols so people cant login using a edited client "that needs recoding on client and server to match up the data".