I have a requirement where we have to Enroll sms as Factor with updated Phone number.
1.Get the Factors list from the user using GET FACTORS --Extract the FactorID.
2.Delete the Existing SMS FACTOR by using DELETE FACTOR - FactorId has to be mentioned in the URL
3.Then use the {{url}}/api/v1/authn/factors?updatePhone=true
This process helped me in deleting the activated SMS factor and enrolling the SMS as MFA with updated mobile number.
Hope this helps.