[Arbico]

You need to save the old skin in the player database
Here is an example. Don't forget to edit it.

PHP код:

#define Skin 30 //This is the skin you want the player to change to when he enters the command
new OldSkin[MAX_PLAYERS];
new Equipped[MAX_PLAYERS] = false;
CMD:equipment(playerid, params[]) {
    if(Equipped[playerid] == true) {
        SendClientMessage(playerid, 0x005500AA, "You have returned to your old clothes");
        SetPlayerSkin(playerid, OldSkin[playerid]);
        Equipped[playerid] = false;
    }
    else {
        Equipped[playerid] = true;
        OldSkin[playerid] = GetPlayerSkin(playerid);
        SendClientMessage(playerid, 0x005500AA, "You have changed your clothes");
        SetPlayerSkin(playerid, Skin);
    }
    return 1;
}