If you signed up to OrderMetrics through the Shopify App store, you have direct login access from Shopify.
You can easily disable direct login to OrderMetrics from Shopify in Settings.
Go to Settings > Manage User Accounts
Select ‘Disable direct login from Shopify’
That’s it! Now you will not be able to login from Shopify. You will only be able to login at app.ordermetrics.io with email and password credentials.
If you want to add new users, click on Add User.
Enter the email and password of the new user.