Are these possible here in THF?

[Agera One]

1) Can I change the primary E-mail ID (with which I registered in Tom's Hardware) to another one?
2) Can I delete/de-activate Tom's hardware account?

 

[Someone Somewhere]

Yes. Should be on your Account Settings page, and the top-most edit button.

You'll then need to confirm the email, and it should be fine.

Not quite sure what you mean by 'activate/de-activate'. You can delete the account, which unlinks all the posts and prevents you from doing anything or receiving any mail, but it's permanent.