Can I 'Flag' problem customers?

I recently had a customer that would like a red flag on his account to ban a specific user. Is there a way to ‘red flag’ a guest account with a note that can only be seen internally (not accessible from the guest end of the account?). This would be specifically helpful if it would flag the account when pulled up on our POS and not just in Admin.

Not quite sure what you want but going into Manage Notes, create a Note and change the dropdown to Flag. This creates a flag that shows up on POS and in the admin panel. Is this what you want?

Thank you!! This is exactly what I need!