If you have tried unticking all of these:
Menu>Settings>language and keyboard>touch input>text input>vibrate when typing
Menu>settings>sound>vibrate
Menu>settings>sound>vibrate feedback
Messages>start an sms>press the language key (shows microphone symbol and language EN or other language)>settings>text input>vibrate when typing
And it is still vibrating when you use a keyboard
Then this is what HTC support advised and it worked for me:
It has been seen on some devices that changing these settings fails to enable or disable the vibration. In this case, it has been found that running the keyboard calibration will force the settings to update and the settings change is saved.
From the home screen, Tap the Menu key
Scroll down, then tap Language & keyboard.
Tap Touch Input.
Tap Text input.
Tap Calibrate.
follow the on screen instructions
it worked for me.