Odoo Enterprise 14

How can I prevent a cashier or odoo user from modifying or editing a specific customer from the contact list?

Typically the POS uses a generic client name; "Public in General" to register sales in this. Sometimes there are customers who want an invoice and in those cases the cashier from the POS registers the customer to specifically bill this customer, registering it as new, or editing the existing customer to update it. Instead of creating a new one, the cashier makes mistakes and modifies the customer established by default and generates chaos in all stores. 

What do you recommend so that no one can edit or modify the "General Public" client that is established by default in the POS?