[Calgon]

With zcmd:

pawn Code:

CMD:admincommand(playerid, params[]) { 
   if(/* your admin level variable */ >= 3) { 
      SendClientMessage(playerid, 0, "You can use this command, you're a level 3+ admin, but it does nothing other than send this message."); 
   }
   return 1;
}

You need to replace '/* your admin level variable */' with the variable you created for admin levels.