I want to close my just-opened-by-mistake self employed account. since I did not put my billing information yet, the instructions of how to close don't apply. Any ideas?

I'm happy to see you here in the Community, @mickeydino.

Allow me to provide some insights about cancelling your QuickBooks Self-Employed account.

The best way to stop a trial version of QuickBooks is to wait for the 30-day trial to end. It will make the account inactive, and there'll be no other charges since you haven't entered any billing details.This is because cancelling an account isn't an option for us, once you've subscribed to a free trial version.

However, here's a link that provides complete steps that you can perform to cancel a paid QBSE subscription: Learn how to cancel your QuickBooks Self-Employed subscription in the app store.

I'm also adding this help articles that you can always scan through to guide you in utilizing the program: QuickBooks Self-Employed Overview.

I'll be right here to assist you if you have any other questions. Just leave a reply below. Have a lovely day!