Log into the Stripe account.
In the upper right corner, click the profile menu icon and select Profile.
Enter the new email address in the Email field and click Save.
Check the new email address for a confirmation email, and click the link in the email to confirm the change.
Use the new email address to log in going forward.
If you are looking to give ownership of your Stripe account to someone else, see Transferring Ownership of a Stripe Account.