Yes, you can actively delete your HTC account anytime.
On HTC account website (account.htcvive.com), sign in first to your HTC Account. Go to the bottom of the profile page and click Delete my HTC Account and data. You'll then see the account termination page.
Please read through the termination details and statement carefully, then follow the instructions on the page if you're certain about deleting your HTC Account. This action cannot be reversed.