If both accounts are active, I'd suggest using the active one that has the company information, which includes the transactions (with customers & vendors) and already has the accounting information such as reports.
Here's how to check the account's status:
Go to the Gear on the top right.
Select Account and Settings.
Choose Billing & Subscription.
Also, you can utilize the left panel to open customer (Sales menu) and vendor (Expenses menu) transactions and reports. Also, you can select the Dashboard menu to review the session you've made previously.
If you wish to cancel an account, you can sign in to the account and follow these steps below:
Go to the Gear icon and choose Account and Settings.
Select Billing & Subscription.
In the QuickBooks section, click Cancel.
Click Continue to Cancel, then Continue to Cancel again.
Answer the short survey, then Click ConfirmCancel.