new findid;
COMMAND:find(playerid, params[])
{
    if (!IsPlayerConnected(params)) return SendClientMessage(playerid, -1, "You have entered an invalid ID!");
    SetPlayerColor(params, 0xAA3333AA);
    findid = params;
    SendClientMessage(playerid, 0xAA3333AA, "The player you want to locate is in red! (the color of this text)");
    return 1;
}

COMMAND:cancel(playerid, params[])
{
    if (!IsPlayerConnected(findid)) return SendClientMessage(playerid, -1, "This player does not exist, or is no longer connected.");
    SetPlayerColor(findid, /*your color here*/);
    return 1;
}