This video shows how to remove Jailbreak or Unjailbreak your iDevice running ios 8.1.2.
Please watch the video carefully most of the time it is self explanatory. You just need to sit back tight and wait for the procedures to complete.
Just remember to have a backup of your device prior to Jailbreak like I showed you in my Jailbreak video here
So at the end of all the above process you need to run your iDevice through that back up only.