An account can have several active users, but there is only one owner. Only the owner can delete users and can make someone else the owner of the account.
If you want to make someone else in charge of the account. If the email address has not been added yet as a user, you can add them by clicking on the 'Add new user' button on the Users page.
When the user has activated their account, you can click on the ‘Make Owner’ button next to their email address on the Users page. They will now be in charge of the account.