Can't able to update Admin permission using API

We can able to change the permissions of the user i.e., SuperUser, Financial using the below API it is working fine but whenever we are trying to change the permission type as admin we are getting below error.
URL : 'https://api.clarizentb.com/V2.0/services/data/objects/User/6d5c76af-9507-4f01-a73f-ec61a53a3e87'
Body:
"LicenseType":"Full",
"superUser":false,
"financial":false,
"Admin":true
{errorCode: "InvalidOperation", message: "Invalid operation: Field 'Admin' cannot be updated. The field is marked 'read-only'."},