Please follow the steps given below to terminate your Site24x7 account.
Login in to Site24x7
Navigate to the Admin > My Account > Account Settings > Terminate my Site24x7 Account
Provide the reason for termination from the drop down and enter the captcha.
Click Terminate my Site24x7 Account
Site24x7 is a service from Zoho Corp. and uses Zoho Accounts for single-sign-on to handle your personal account settings. Deleting an account in Site24x7 is not the same as closing your Zoho account. They are deleted only from Site24x7. If you do not use any other Zoho Services and want to terminate your Zoho account, please read this article.