How do I change my Alias domain to a Secondary domain?

If you previously added a domain as an Alias and need to change it to a Secondary domain configuration, you can remove and re-add the domain, no migration required! Nothing is deleted (except for the users' Alias addresses). 

Process:

  1. remove alias domain (eg. acbcorp.com) (https://support.google.com/a/answer/183028)
  2. add acbcorp.com as Secondary domain (https://support.google.com/a/answer/7502379)
  3. add alias emails (eg. will@acbcorp.com) to users as needed (https://support.google.com/a/answer/33327)