Hey Chris! If you have collaborator access to a store then you should be able to sign into the admin for this store directly from within your partner account. If the login page is still redirecting you to this deactivated account though, I recommend doing a full browser cache and cookie clear and attempting to follow the email once more.
If for any reason this is still causing you a problem, please connect with our partner support team through your partner dash for further troubleshooting.