To remove editable in tree view you must use only tree string like below :

<tree string="Phone Calls" >

if you want to remove via inherit then try below exmple:

        <record id="view_form_editable_list" model="ir.ui.view">
        <field name="name">objectt.form.editable.list</field>
        <field name="model">object.object</field>
        <field name="inherit_id" ref="view_ref"/>
        <field name="groups_id" eval="[(6, 0, [ref('groups_if_any_in_tree_view'),ref('groups_if_any_in_tree_view'),])]"/>
        <field name="arch" type="xml">
            <xpath expr="//field[@name='one2manyr_line']/tree" position="attributes">
                <attribute name="editable"/>
            </xpath>
        </field>
    </record

In groups_id you can add that groups which are in tree views fields so when this all applied group is active then editable is removed from tree view.