Dynamics 365 "Owner account" or Service Account for the service

Hi,

Is there a "owner" account or service account or similar in Dynamics 365 that can't be deleted?

I have a customer that is unsure about this and I can't find any information regarding it. They don't want to be in the position of removing a account and the service stops working.

My feeling is that there is no such special account and as long as there is a user in the "System administrator" role in Dynamics 365 all is well.

What is your thoughts on this?