patch
https://api.infinicept.com/api/api//merchant//contacts/primary
Updates the primary contact on the Submerchant Profile of a specified submerchant within a Backoffice tenant using the replace operation. A primary contact must exist for the submerchant to use this request.
Fields that can be replaced include /FirstName, /MiddleName, /LastName, /PhoneNumber, /Email, and /Title.
Use POST Add a Contact to a Submerchant to create a primary contact. Only one primary contact can exist on the Submerchant Profile.