You will need to have saved SHSH Blobs for iOS 5.x and iOS 4.x for this tutorial to work.
Create a folder on your desktop called Pwnage
Download the latest version of RedSn0w from here and place it in the Pwnage folder. Likewise, download the 5.x firmware you would like to restore to and the 4.x firmware you have saved SHSH Blobs for from here and place it/them in the Pwnage folder.
Extract the RedSn0w zip file by double clicking it.
Right click or control-click the redsn0w application from the redsn0w folder we extracted earlier and choose Open from the popup menu that appears.
Click Extras from the main menu.
Click Even More from the Extras menu.
Click Restore from the Even More menu.
Click IPSW from the Restore menu, choose the IPSW you would like to restore to from the window that appears, and click Open.
When prompted, connect your iPad 2 to the computer in normal mode and click OK
You will be informed that a 4.x IPSW will be required to continue. Click the OK button.
Select the 4.x firmware IPSW from the Pwnage folder on your desktop and click Open.
Your iPad will now be placed into recovery mode.
RedSn0w will check Cydia to see if you have the correct blobs saved.
If RedSn0w is unable to find your blobs automatically click the Remote button to try again or you can click the Local button to search for blobs on your computer.
RedSn0w will prepare the 4.x restore image.
You will then be prompted to place your iPad into DFU mode. You can find more help with DFU mode here.
Hold down both the Home button and the Power button for 10 seconds.
Release the Power button and continue holding the Home button for another 10 seconds. You screen should stay blank.
Click the OK button to continue.
RedSn0w will now restore to iOS 4.x.
Once the restore to iOS 4.x is complete, RedSn0w will put your device back into recovery mode and prepare the iOS 5.x restore image.
iOS 5.x will now be restored.
You'll be notified once the restore is complete.
If you need help with this tutorial please post a question in the comments or submit a question to the iClarified community using our Answers section.