On the website (upper right hand corner under your name, settings), you can edit your personal details, email address, units displayed (imperial/metric), notifications and email subscriptions. You can also change your password.
Please note that it is not possible to change the username. You have to create a new account in order to have another one.
Unfortunately at the moment it's not possible to delete the account, but it will be added as soon as possible.
Contact Us inside the app
Android: Settings - Help
iOS: Profile - Help & Feedback
Or use this Form
Phone service is not available