You can change the Stack name by going to Settings > General and amending the existing name. Once the name has been changed, click Save and the Stack account's name will change on the top left-hand side of the account.
Note: this does not change the stack URL. Be sure to remember your new stack name, as this will be needed when creating a support ticket.
For any further questions or queries, please send an email to firstname.lastname@example.org and our support team will get back to you.