The white-label merely removes the Invoice Ninja branding from the invoices and client-facing areas. Removing all branding is part of the reseller program.
"The white label license is intended for personal use. It only removes our branding from client facing parts of the app, joining our reseller program enables you to remove all of our branding."
– At the client side (!) the title says: Invoice Ninja – Free Open-Source Online invoicing
To add to Titanfail’s answer: the reason you are having that behavior on the client side is ONLY when logged in to the system, else it would now show Invoice Ninja anywhere on the client side.