We’re working on the ability to change the SharePoint site URL associated with an Office 365 Group.Stiliyan commented
Not able to find the same on the roadmap. It was considered unnecessary...
To change the email address of the group, follow the best answer here: https://answers.microsoft.com/en-us/msoffice/forum/msoffice_o365admin-mso_exchon-mso_o365b/how-to-add-an-email-alias-to-an-o365-group/79d94383-442a-4e3a-ac62-4ff1ea8af962.
We’re working on renaming the Team Site. Stay tuned.