Today my pad stopped functioning correctly, even when the left stick is in neutral position, the up direction is permanently pressed. This means my character is always jumping nonstop.
After wrestling and pushing the stick, it returns back to normal but after a few seconds it goes back to press “up” continually.
Should I disarm the controller? Can I “reset” the y axis or recalibrate the pad in some menu? Or is it time for a new pad?
Did you try turning it off and back on? Turning off the Xbox? Better yet,just tap up or hold it for a while and stuff. Maybe you might need a new pad though.
You might be able to open up the controller and clean up the pad from within. Or remove the analog stick entirely. It can be a pain in the buttocks to put it back together so pay close attention to what part goes where. 
Same thing happened with my Day 1 controller, nothing you can do unless you want to void the warranty. You could try contacting MS about it although I’m unsure if they would fix it. Only other option is a new controller I’m afraid
You can try and clean it with 91% alchohol and a cotton swab. But if that doesn’t work…just get a new one. Game stop trade in right now on Xbox one controllers is $26.80.
New controllers have a 3.5mm head set plug so you don’t have to have an attachment. Just plug straight in. so its worth it in the end.
You could also try to update it in the settings/accessories.
I very recently had a problem with my controller’s mic port and Microsoft sent me a new one for free (after receiving and processing my defective one). It took about 2 and a half weeks from opening a support ticket to getting the new one. I did have to pay the shipping to send it to them though and I was short a controller while waiting for the new one. Definitely worth a shot to contact them and try for warranty repair.
Just ordered a new pad on Amazon, killer deal since it cost me 47$
Thanks everyone for responding.