In order close or remove your account, you must log in to your control panel. Normally it is https://my.iSpyoo.com (some cases it is other sites for more security depend on what you offer for big customers), and then go to the menu on top/right: Account Information. You will see sub-tab Remove Account.
With this page, you must confirm again your password to make sure you want to close your account and then click button Remove my account.
After removing you will be redirected to sign in page (sign out) and all data including device linked, your account data logs, the email address associated with our system will be removed immediately.