implement ability to delete users on admin dashboard (DeleteUser.tsx)

[RyanS4]

• Should be in a similar display as the create user page
• Should have a textbox that takes in a username, a delete account button, and a back button
• Back button should return the user to the admin dashboard
• delete button handle should read the username from the textbox and delete that user from the database
• User should not be able to delete their account