Good morning, @s12199733-studen.
Congrats on making your first post here in the Community. I can help answer your question about how to purge/delete your data and start over in QuickBooks Online.
If you've had your QuickBooks Online account for more than 60 days, you'll need to create a new company. Also, if you're paying for a subscription at this time, you'll need to cancel your current account first before starting a new one.
Review this guide for the steps and more details: Delete your data and start over in QuickBooks Online.
This should do the trick and answer your question. I'm only a post away if you need me. Happy Monday!