Return to stock Htc One

So I've had this One m7 for 2 years now and have gotten a new phone. I plan to give it to an older member of my family but will ned to return to stock before I can any help?
BTW: I am S-On since I cannot gain s-off due to the H-boot limitations (trust me i have tried)
H-boot 1.61

any help would be greaty apprectiated thank you.