Exclamation [Q] Help switching to stock recovery

I Recently Bought an Htc one (M7) {running android 4.3} from an electronics shop well 4.4 Kitkat Just came out so I was all excited to update to check out all the changes... sadly I was mistaken. The previous owner had tried to root the phone so im stuck with a phone that is "Tampered" "Unlocked"
with "s-on" not to bad right? well the recovery on the phone is Team win project recovery... and the phone is not rooted

I want to return the phone to stock or at least beable to get normal ota updates

Can some one give me a detailed step by step walkthrough of how to switch the phones recovery back to stock im not very tech savy in this field