How do I take 1 OF 2 OS off my Desktop ?

I have Windows XP professional 2002 SP3 and XP Pro-SP3 2011, i have both installation disks but nether give the option to delete.Cant find it in Add and remove program. I wont rid of the XP SP3 2011. When i start up my computer it gives me 30 sec to pick which one i wont to start and my XP SP3 2002 been acting funny ever since. i thought it would overwrite my 2002 but it didn't and i am glad it didn't because i like the 2002 better. Please help !