That is not currently possible and actually violates the license, at least under the community self-hosted edition.
You are allowed to use n8n for your own business uses but are not allowed to “white label” n8n for your customers.
don’t worry though! n8n supports us freelancer and agency owners. See my previous reply here for an in depth explanation. What i explained there was later confirmed by the founder Jan.
There is also a thread here where active community member and long time n8n pro BramKn discussed it in this thread
I recommend reading through those and your questions will likely be answered!