[Konstantinos]

You asked for a way, and it was given..

Anyways, you can understand what part you should get:

pawn Код:

#include < a_samp >

native IsValidVehicle( vehicleid );

public OnPlayerCommandText( playerid, cmdtext[ ] )
{
    if( !strcmp( "/delallveh", cmdtext, true ) )
    {
        for( new i = 0; i < MAX_VEHICLES; i++ )
        {
            if( IsValidVehicle( i ) ) DestroyVehicle( i );
        }
        return 1;
    }
    return 0;
}