ClackID runs your account
You sign in to chastity.report with your ClackID account, so a password is never typed here. A forgotten password, a new email address, a passkey and the ways you sign in are all on ClackID, and its help page answers them.
Your email address
Emails from chastity.report go to the address on your ClackID account. Change it on ClackID, and it comes through here the next time you sign in.
Asked to sign in again
Downloading a copy of your journal and deleting it both ask ClackID to check it is you first, even when you are signed in. That is on purpose: anybody holding your phone could otherwise do either.