[fuckingcruse]

Ok , so its easy make a variable

new IsInRace[MAX_PLAYERS];

And in the race cmd type

IsInRace[playerid] = true;
Make a cmd to leave it

And in that leave cmd type
IsInRace[playerid] = false;
And in OnPlayerCommandTest
Blah blah blah
On strcmp your race cmd

Type the race cmd && the leave cmd

And if(IsInRace[playerid])
And only leave cmd is allowed

This is how to disable all cmd except /leave

I made such topic here
https://sampforum.blast.hk/showthread.php?tid=568097