Everything here is in your profile settings.
Your profile image, username and email address. Changing your email means confirming the new address before it takes effect.
Changing your password asks for the current one. If you have forgotten it, request a reset and Piczel emails you a link to set a new one.
Signing up sends a confirmation email. Opening the link confirms the account and signs you in on that device. Ask for another confirmation email if you need one.
At the bottom of the same page, in the danger zone.
Deletion removes your account and all associated data. It's removed within a few minutes, and you'll get an email when it is done.