First, unlink your Google account from Ringly.io. Go to your Google settings, click “My Account”, select the Security menu, find “Third-party apps with account access”, and remove Ringly.io’s authorization.
Next, go to Ringly.io’s login page and click “forgot password”. Use the password reset flow to create a new password for your account.
Then check by logging in (not using “continue with Google”) with your new password. You will still see the Google logo in your account settings, but it will not be connected to Google anymore