Can you turn off Sense UI or Moto Blur? That answer to this question will be your answer.
HTC took away the option for turning of Sense on the EVO.
You can't turn off touchwiz, but I really don't see why you would want to. It is more or less good, and if you don't want it just flash a vanilla rom.
I want to turn it off because the borked the calendar. You can't select phone numbers in an appointment - I have to copy and paste the text and then copy the phone number and paste it into the dialer. It is like using an iPhone from 2 years ago.