If you want to close an Airbnbaccount, you can easily do that in the Settings page of your account.
I’ll show you below with pictures how I managed to remove my profile (using a desktop computer):
1 Go to airbnb.com and login to your account
2 Click on your name and select “Account”
3 Select Settings in the left menu
4 The Cancel my account can be found here
5 Tell them why you’re leaving and cancel again
A message appears: “Your account has been canceled”.
Source screenshots (and thanks to): airbnb.com