There are no features in blogger dashboard to do this but there is a tricky way to make it done.
1. Sign in and go to your blogger dashboard.
2. Go to Settings > Basic
3. Click
+Add authors, type any new preferred email and click
Invite Authors.

4. The new email will received the invitation and accept it.
5. Make the new authors as admin. You can now remove the old authors by clicking the
X button