how to restore mac air late 2010 to its factory settings?

Welcome,

To restore the Late 2010 MacBook Air to factory settings:

1. Insert the OS X thumb drive that came with your computer, hold the Option (Alt) key while your computer is starting and choose your USB drive.

2. Choose your language, and go to Utilities menu > Disk Utility.

3. Select "Macintosh HD" on the sidebar, go to Erase tab and erase the disk. This will delete everything that it's in the hard drive.

4. Close Disk Utility and reinstall Mac OS X. Remember to install the iLife applications from the thumb drive after installing OS X

Take a look at this link, http://apple.stackexchange.com/questions/13954/how-to-factory-reset-a-2010-macbo ok-air

If you are using Mac OS X 10.7 or greater then you can restart you computer by holding down the command + R then follow the erase and reinstall or Mac OS X.