Hello there, @Bonnieo1.
Thanks for reaching out to us here in the Community. Allow me to step in for a moment and share some additional information about the error you're getting when deleting an account in QuickBooks Online (QBO).
This sync error occurs when an account was deleted in Bill.com that is associated with a Form 1099 box in QBO. This prevents the sync from being able to delete the account. To fix this, the account will need to be removed from the Form 1099 box.
Here's how:
1. Go to the Expenses menu on the left pane, then select Vendors tab.
2. Click Prepare 1099s in the upper right.
3. Choose Continue your 1099s.
4. Navigate to the Accounts page.
5. Locate the specific account.
6. Update the account to a different account or uncheck the box(es) that are required for tracking.
7. Click Save and Finish Later to close the window.
For your reference, you may visit this link for more information: QuickBooks Online Sync Error: Business Validation Error: You cannot delete an account that is associated with a Form 1099 box.
Those steps should help you delete the GL account in your QBO.
Please let me know how it goes or if I can be of additional assistance. I want to make sure this is fix. You take care!