Under the menu ☰ you will find the settings page. This page has a tab named Accounts where you can edit existing accounts.
The Accounts tab shows a list of all Lytho users and their information like e-mail, name, role and status. To edit any of these values, click the edit-icon (pencil) to open the user settings.
Tip: You don't need to delete a user account to decline someone access. An account can be disabled in the user settings instead.