Hi there, userhajizafar337g.
If you want to start from scratch, we have a way to purge your account. This can be possible if your books are less than 60 days old.
Note: Please don't use the steps below if you are using the QuickBooks Online Accountant version. This will cause damage to your account that we can't undo. Instead, import a blank QuickBooks Desktop file to start over.
For books that are 60 days old or older, you'll want to delete the customers and vendors manually.
Here are the steps:
Otherwise, cancel the current account and subscribe to a new company.
You can read this article for more information: Delete your data and start over in QuickBooks Online.
If you have additional questions or other concerns, please let me know by adding a reply below. I'll be right here to help you out again. Have a good day!