How to delet un-used compnies?

Hi there, @userps14691708. 

As an insight, you can cancel the unused account and the data will be wiped out automatically after a year of being inactive. 

Here's how to cancel:

1. Click the Gear icon and select Account and Settings.
2. Click Billing & Subscription, then select Cancel your trial.
3. Click Continue to cancel and follow the steps on the screen.
4. Select Submit and cancel subscription.
5. Click Got it.

Once done, you'll receive an email that confirms we canceled your subscription. 

For additional reference, you can also read this article: Delete your data and start over in QuickBooks Online. 

You'll want to consider exporting all your data for your future use. Here's an article for your reference: Export reports, lists, and other data from QuickBooks Online.

Feel free to post again here in the Community if you have additional questions, @userps14691708. I'll be around here to help some more,