Even after I deactivated the custom fields, they are still showing up in the Customer section

In QuickBooks Online, the system is designed to protect your data. If a custom field is set to inactive, it will still appear in the Edit Customer window as long as any information remains in that field for the customer. This helps prevent the accidental loss of important notes or data.

To completely remove your custom fields from the Customer Information window, delete all information from it.

If you have further questions or concerns, please feel free to reach out. We are always here to help.