Rename of namespace

Hi,

   I have a new Azure subscription so I want to migrate my Azure Active Directory. I created a new one and copied (manually) everything on the older one to the new one.

   However, all my code points to the old one and I want to avoid making code changes for this.

   So I would like to rename the new one so it can have the name that the old one has.

    However, I'm not able to do so. I was thinking on first renaming the old one so I can use its name but I don't know how to do that.

    Can anybody help me or provide me the MS email of somebody who can?

    Thanks!