It's nice to see you here, @developmentmari-,
Yes, you can still delete the whole file if it's within 60 days old (90 for non-US accounts). To reset your company data:
Here's an article that contains all the information about the process: Delete your data and start over in QuickBooks Online.
However, if it's active for 90 days or more, terminate your account directly on your QBO profile. Here's how:
For information and instructions on how to cancel a QBO account, see this link: Cancel your QuickBooks Online subscription.
However, if you were billed for the duplicate company and want to discuss refund agreements, please contact us directly. Our phone representatives can pull up your account with us and can provide more information about your billing.
Here's how to contact Support:
If you have any questions, please feel free to post them here or mention my name. I'll be here to help at any time. Have a nice day!