If you mean restarting your company file and start over from scratch, you can purge your QuickBooks Online (QBO) account. Please know that this process will only take effect if your account aged is less than 60 days. Also, it only works for QBO Plus and Essentials version.
Here's how:
Log in to your QuickBooks Online account as an admin.
Change the URL in your browser's address bar. For example: