To use another email address to log in to your TWICE account, you may add a new admin user and remove the old one.
Step 1: Add a New Admin
Go to Settings > Users & Permissions.
Click New User and select the Admin role.
Enter the new email address and click Invite.
Accept the invitation with the new email and set a password.
Step 2: Remove the Old Admin
Log in with the new email.
Go to Users & Permissions and delete the old admin account.