By error I created 2 accounts: one for trial and one that I want to confirm with Simple Start. Can you please help me to cancel the trial account? Thank you.

These steps will work:

Gear icon > accounts and settings > billing & subscription > cancel quickboks trial

Glad to see you here in the Community, @alex-thegildedig.

I can help cancel your trial account in QuickBooks Online (QBO). We can perform this by going to the Billing & Subscription page. Make sure to sign in as a Master/Company Administrator to cancel your account.

Here's how:

1. Go to the Gear icon.
2. Under Your Company, choose Account and settings.
3. Select the Billing & Subscription tab.
4. Click Cancel your trial.
5. Select Continue to cancel.
6. Follow the on-screen steps.
7. Select Submit and cancel subscription.
8. Click Got it.

Once done, we'll send the account administrator an email that confirms we canceled your subscription.

To help you get started, I recommend visiting this website: QBO Basics. You'll watch step-by-step videos to help you efficiently manage your income, expenses, inventory, and banking in this link. 

The Community is always here if you have other questions. Thank you and have a great day ahead.