The Reset Account feature provides you with the ability to bring your account to the same state as it was when you just set it up, deleting all files, databases, email accounts, and any other settings like domain redirects.
Account reset cannot be undone - make sure to download backups of your files and databases if needed before proceeding. You can also back up your email messages using Webmail.
You can reset your account by opening Websites → Dashboard, search for Reset Account on the sidebar, and click on it:
Next, read the warning, double-check the list of websites that will be affected, and click Reset:
As soon as you click Reset, your account will be wiped clean.
NOTE
If you would like to delete only some data, you can remove files via the File Manager and databases via hPanel