It's a pro feature.
1.Visit >Woocommerce>Phone Orders>Settings>"Run at frontend" and mark first checkbox, probably you have to mark both "hide xx" options too .
2. Use plugin https://wordpress.org/plugins/user-role-editor/ to create new role
3. Add capabilities "manage_woocommerce_phone_orders" , "edit_shop_orders" for this role.
Your users should visit http://yoursite.com/phone-orders-frontend-page ( this url is editable).
If you will sale complex products:
1. Use code from this section
2. Visit >Woocommerce>Phone Orders>Settings>"Run at frontend" and mark checkbox "Allow to configure product"
3. Visit http://yoursite.com/phone-orders-frontend-page , select product and use button "Configure Product"