You can sign in to Planner with your Google account instead of an email and password.
How to sign in
Go to planner.routal.com.
Click Continue with Google.
Choose your Google account and accept.
See how you sign in
In Settings → Profile, under Sign-in methods, you see whether your account uses a password, Google or both.
For administrators
In Settings → Organization → Users you see next to each person whether they sign in with Google. If you disable someone's Google account in your company, they can no longer sign in to Routal with Google. If they also had a password, deactivate their user in Routal too.