Go to your settings page "My Account > My settings" and upload a photo. If you have already a photo at [Gravatar.com[(https://en.gravatar.com/), then is taken automatically. But you can always choose a different photo by manually uploading it.
If your password does not work you can request a new password at the login page. You will then receive an email to verify that you are the owner of the account to select a new password.
Yes, you can delete your profile, but not your contributions such as ideas and comments. That is up to the administrator to remove your contributions, who is responsible for your community. You need to contact him or her.
To delete your accounts go to My account > My settings and click the red button at the button.