How do I restore my 2011 MacBook Air to its original settings?

How do I restore my 2011 MacBook Air to its original settings for resale? When I do the cmd R and go through the process, it begins the restore process for Mountain Lion because I upgraded to Mountain Liion on this machine a few months ago. And it's asking for my Apple ID. If I do that upgrade, the buyer will have a version of Mountain Lion that is associated with my Apple ID and that won't work. Also, isn't there licensing issues in such a case? I want to restore the MacBook Air to its original factory settings when I purchased it in April of 2011. At that time it was Lion and not Mountian Lion. And I don't want any software on this computer to be associated with my Apple ID.

Thanks for all your help.

Ron