There must be at least one business in your Billdu account.
Take a look here of you want to delete your entire Billdu account.
IMPORTANT NOTE: This action will delete all your documents saved in the business and can't be undone.
NOTE: A special anti-fraud law that applies for French and Spanish businesses may prevent you from deleting a business
Switch to a business you'd like to delete
Got to Settings
Open the Business settings
Scroll down
Click on Delete business
Type the word "Delete"
Confirm with Delete button