Hi,

It looks like; you are supposed to create a new user(or use an existing user if you have already created one) for the cashier and you need to limit the access for the user to only Point of Sales and Attendances.

This can be achieved using security groups in Odoo.The Apps listed in the home page are also menu items in Odoo. We can add security groups to the menu items, which eventually limits access to those groups. In your case, you can create 1 security group for the cashier and add the user to the group, and add the group to the menu items of Point of Sale and Attendances. It is possible to have some groups already listed in the Access Rights tab in the menu items. You have to carefully manage the security group to limit the access. If you remove existing groups, the users who have access to those menus cannot see them. So, add the new group there.
Some modules like Discuss and Website(If you have already installed) have their menu which can be accessed by all internal users. In this case, you have to remove the group(Internal Users) and add a new group with all internal users without the cashiers. This step can be used to hide the App menus.

To manage access to the menus and submenus inside the Apps Point of Sales and Attendances, you have to follow the same process.

In case, if you need to restrict the point of sales(pos.config) to the cashier, you can add record rules.

Regards