Edit Account Information
Clicking on the edit profile page will allow you to edit the email address, username, and password associated with the account.
If you have the option to change the password, you have only an iFixit.com account and you can also change the email address.
If the email input box has your current email address listed but it is grayed out and you cannot see a box to change the password, you used another service to log in.
If you would like to dissociate your Google account from your iFixit account, go to myaccount.google.com > Sign-in & Security > Connected apps & sites > Manage Apps > iFixit > Remove.