server-tools/base_user_reset_access/views/res_users_view.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
	   <record id="view_users_form" model="ir.ui.view">
            <field name="name">res.users.form (base_user_reset_access)</field>
            <field name="model">res.users</field>
            <field name="inherit_id" ref="base.view_users_form" />
            <field name="arch" type="xml">
                <xpath expr="//group[@string='Allowed Companies']" position="before">
                    <button name="reset_access_right" string="Reset Access Right" type="object"
                        confirm="This will reset the user's access rights to the minimum configuration. Are you sure?"/>
                </xpath>
            </field>
       </record>
    </data>
</openerp>