partner-contact/partner_default_sale_discount/views/res_partner_view.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
  <data>
    <record id="view_partner_form" model="ir.ui.view">
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form"/>
        <field name="arch" type="xml">
            <field name="user_id" position="after">
                <field
                        name="default_sale_discount"
                        attrs="{'invisible': ['|', ('customer', '=', False), ('parent_id', '!=', False)]}"
                        groups="sale.group_discount_per_so_line"
                />
            </field>
        </field>
    </record>
  </data>
</openerp>