Motivation
The BN API supports updating custom domain: https://internetcomputer.org/docs/building-apps/frontends/custom-domains/using-custom-domains#updating-a-custom-domain
In case you want to update the domain to point to a different canister, you first need to update the DNS record of your domain, then notify the custom domains service ...
The Console does not yet support transferring domain. Probably not the priority but, it's a feature we can support in the future.