About withdrawing my parents' green card application

My parents' green card application is current based on new visa bulletin (family - F4 sibling from Aug 2002).
Now they decided to go back to China and not to get the green card since it's easy to obtain B2 visa now and 10 year now.
My question is, do I have to file anything to USCIS to let them know they want to withdraw from their application?
Will this effect they future green card application if they do change their mind in a few years? (I will be sponsoring them instead of my dad's sibling)
If I do apply for them in the future, which family class should they belong to? (parents of US citizen, I don't see that prior date from visa bulletin) and how long will it take?
Thanks.

所有跟帖： 

• Reply -863211- ♂ (1635 bytes) () 05/13/2015 postreply 15:53:48

• Can they switch sponsor from my father's sibling to his son (me) -bryanmeow- ♀ (0 bytes) () 05/14/2015 postreply 09:54:26