I Got the solution for above problem.
For that you could just find and edit that kanban view in order to remove this attr: on_create="crm.create_opportunity_simplified"
You could do it easy with developer mode activated by editing the kanban view in that menu.
If you wanna do it in a module with xml view inheritance, you could do it like:
<record id="crm_case_kanban_view_leads" model="ir.ui.view">
<field name="name">crm.lead.kanban.lead</field>
<field name="model">crm.lead</field>
<field name="inherit_id" ref="crm.crm_case_kanban_view_leads"/>
<field name="arch" type="xml">
<xpath expr="//kanban" position="attributes">
<attribute name="on_create"/>
</xpath>
</field>
</record>