[Guitar]

How about this?

pawn Код:

CMD:skinset(playerid, params[])
{
    new skin, sendername[MAX_PLAYER_NAME], string[128];
    
    if(sscanf(params,"i", skin)) return SendClientMessage(playerid, COLOR_RED,"[ADMIN] /setskin [SkinModel]");
    if(skin > 299 || skin < 1) return SendClientMessage(playerid, COLOR_RED, "You've inserted a wrong skin ID. Choose from 1-299");
    
    if(skin == 1) return SendClientMessage(playerid,-1,"You can't use that skin, choose another."); // Here put the skin ID you want to forbid using.
    
    GetPlayerName(playerid, sendername, sizeof(sendername));
    format(string, sizeof(string),"Your skin ID now is %d", skin);
    SendClientMessage(playerid, 0x47568497, string);
    SetPlayerSkin(playerid, skin);
    
    return 1;
}