Assuming you saved your SHSH blobs for the last firmware susceptible to an untethered jailbreak, you can follow this video tutorial and downgrade to iOS 4.3.3 in about 10-15 minutes. Inside we show you how, step-by-step…
How to Downgrade iOS 5.0.1 to iOS 4.3.3
Note: This is assuming you have your SHSH blobs saved for iOS 4.3.3. This uses the latest version of RedSn0w 0.9.9b8, TinyUmbrella, and iTunes. You can get the iOS 4.3.3 or below firmware from our Downloads page.
Step 1: Put your device into DFU mode.
Step 2: Verify that your Hosts file is devoid of any Apple references (see video)
Step 3: Open RedSn0w > Go to Extras > Click PwnedDFU. Your screen should remain black on your iDevice.
Step 4: Open TinyUmbrella, click Start TSS Server
Step 5: Open iTunes hold Option+Restore (Shift+Restore in Windows) and select the iOS 4.3.3 Firmware.
Step 6: If you receive Recovery Error (1), close out of iTunes.
Step 7: In TinyUmbrella click Advanced and uncheck “Set Hosts to Cydia on Exit…” Close TinyUmbrella.
Step 8: Open RedSn0w > Go to Extras > Click Recovery fix. Your screen should look as if the device is being jailbroken. It should then go back to a solid black screen.
Step 9: Open RedSn0w > Go to Extras > Click Just boot. Your device will now boot and you should see the Pwnapple logo. Your device should now be successfully back on iOS 4.3.3
Step 10: Open iTunes to activate your device.
As always, we strongly recommend watching the video walkthrough for more verbose details. Have you tried to downgrade your iOS 5 device yet? Did you do so because of the untethered jailbreak, or for other reasons?