How do you unauthorized a computer for itunes?

How can I sync my iPhone with another computer's iTunes program?

• Ok so i have an iPhone 3g and i have had it synced to my computer since i've first got it. well, my friend has just a normal ipod and she has it set to where she manually manages her music and videos. and she can plug her ipod into other peoples computers and get songs off their computers. if i plugged my phone into someone else's computer it wouldn't allow that bcuz my iphone is synced to my computer. so i plugged my iphone into my computer and unchecked the little box that said "automatically sync this iphone when connected" and i also unchecked the little box that said "sync only checked songs and videos". then, i checked the box that said "manually manage songs and videos". i wanted to be able to plug my phone into other peoples computers and get songs from their itunes. So, i tried to get songs form someone elses computer and the same message popped up that said that my iphone was synced to a differnt computer so the only way that i could get music onto my phone from a different computer would be to erase everything that was on my phone from my own computer. why am i not allowed to get songs from other people's computer like my friend is when our settings are the same?

• Answer:

  no you cant