Change from default TFN to new 10DLC

Hi...we're using Cognito and sending MFA codes to users via SNS. We started with the default TFN but experienced long delays in deliverability so we applied for a 10DLC. Now that our 10DLC has been approved we want to start using it. My question is: how do I switch from using the default TFN to our new 10DLC? I've looked all around the SNS and Pinpoint consoles but I don't see any options to change the default number. It appears that in Pinpoint console it allows me to delete the default TFN, if I do that will my 10DLC become the default? Please help.