Do this:
- On your phone, create an instagram account using Facebook log in.
- Now on your desktop web browser, log in using Facebook connect.
- Now go to delete your account - edit profile -> I'd like to delete my account.
It will ask for your password.
But you never gave it a password in order to create the account.
I tried using my Facebook password, but that didn't work.
Any ideas? The Instagram account management seems quite broken.