HTC One won't stop vibrating!
Weird that none of those settings worked. I would recommend lowering the vibration intensity, since it is a stock option on most HTC One devices now.


  Go to Settings – Sound – Vibration intensity. Then slide the bars
  left or right to change the intensity.


Referenced here

Other places to check: Settings - Sound &amp; notification - Other sounds - Vibration intensity

If your device does not have that option, I have used FauxClock on my HTC One M7 to adjust it via root: Faux123 Kernel Enhancement - Google Play



If you have the M8, ElementalX Kernel is a good option: XDA thread It has vibration intensity controls, along with a load of other tweaks for saving battery, improving performance, etc.

If you're a fan of Xposed framework, there is an Xposed module available, but I'm not sure of the device compatibility.

If you don't want to root at all, there is an app called Vybe that records custom vibration patterns without root, see a description here. You'd likely be able to record an "empty" vibration pattern so that your phone doesn't vibrate at all. Can't find it on Google Play, here's another app that has the same function, with good reviews: Vibration Control - Google Play

Hope one of these suits your needs