Create User with REST API returns 401

hello
I want to create a user and the rest api is responding with a 401
First I log in with the user walter.bats and then I send this request

http://localhost:8080/pretty/API/identity/user
post method
payload
{"enabled":"true","userName":"Ulysses.Perez","password":"bpm","password_confirm":"bpm","firstname":"Ulysses","lastname":"Perez" }
The response to this request is a 401, unauthorized
that could be happening? Does the user walter.bats have to have any permission to create a user?

Cheers