i dont wanna go to usa anymore do i have to cancle my green card ? what if i dont ? and im australian citizen?

Phil	Two different issues. You can just let your green card expire, you don't need to return it or anything, I would suggest you keep it because it is proof at least that you held permanent residence and would allow tracing your residency for legal puproses if that ever was necessary. The green gard however is merely proof of the right to reside in the US. That right can be lost by living outside the US for any long period of time, specifically more than one year without taking steps to preserve your status. So you don't need to do anything to lose your permanent residence, but you might change your mind so I suggest you hang on to the green card and don't make any steps to actively forfeiting your rights. They'll go anyway.

David	if you wish to return a green card use form I-407

fatsausage	Leave quietly,

Max Hoopla	Stay home.

Love.Canada	Its not mandatory you go, just leave it