[newbienoob]

title says it all, how can i do that?

[MP2]

You mean when players spawn vehicles? Store the ID of the vehicle that was spawned in an array for the playerid, then next time they spawn a vehicle use DestroyVehicle() before you re-set the ID.

[newbienoob]

show me an example

[[ABK]Antonio]

Here's an example

pawn Code:

new Car[MAX_PLAYERS] = 0;
CMD:car(playerid, params[])
{
    if(Car[playerid] != 0) DestroyVehicle(Car[playerid]); //destroy it, then we continue down the script
    Car[playerid] = CreateVehicle(blah blah blah);
    return 1;
}

[MP2]

No need to put '= 0' in the declaration - variables are always initialized to 0 in pawn.