Hi Ovees,
Welcome to Box community!
It would be advisable to include the new email as a secondary and designate it as the primary email.
The steps for adding or modifying your email address are as follows:
1. Login to box.com
2. Go to Account settings (click the profile pic or initials located on the upper right corner)
3. Account
4. Add a Collaborator or Link Personal Email
5. Link Personal Email > enter the new email
6. Confirm the email
7. Go back to account settings and make the secondary email as primary.
Hope this helps and thank you for posting!