1) Go to https://accounts.pblworks.org/user, and if you aren't already signed in, sign-in with your existing email account.
2) Add a new email address and verify it.
3) Make the new email address your primary email, and remove your old email address if you no longer have access to it.
Also remove any connected Google Accounts that you no longer have access to. You can connect a new Google Account when you sign in for the first time with your new email address.
5) Sign out and sign back in to make sure the new email address works properly.
If your new email address is associated with a Google Account, you can sign in with Google. If not, enter your email address to get a sign in link.
Note: After signing in, you may be taken to MyPBLWorks where you'll need to click "login" again to enter the site.