You can remove a sub-account by switching to the sub-account that you want to remove.
From there on, go to Account settings -> Advanced -> Account removal.
Or follow this link directly: https://app.spott.ai/settings/company/advanced/delete
Click Delete account, after this you will return to your main account.
Before clicking the button, make sure to double-check you are in the right account!
Once an account is removed, all the data is lost forever.