How to remove your ImageShack account
From the FAQ:
It is not necessary to delete your account once you feel that you no longer need it. Simply stop using it. Otherwise send us an email and we will remove it.
https://imageshack.us/content.php?page=email&q=customer
Direct removal link: https://stream.imageshack.us/content.php?page=email&q=customer
Helpful Trick: Removing online data
Publicly visible text/images often aren’t properly removed even when you succeed in removing an account. Try editing or removing them manually before removing the account itself. If you’re unsure what happens to your tracks: this can be found mostly in the Terms of Service/Privacy Policy; otherwise you can always contact ImageShack and ask personally. By the way, removal requests don’t necessarily mean your data will actually be removed (e.g. due to legal obligations).
Helpful Trick: Remove third-party logins
If you signed up for ImageShack using a third-party login such as Facebook or Twitter, you probably want to revoke all access from ImageShack. Click here to find out how.