You can change any xml view by naming id to model_name.id:

here you need to change it as:

<menuitem id="sales_team.menu_partner_form" parent="your_parent_menu_id" action="base.action_partner_form" sequence="3"/>

You can also achieve the same if you create a new menu item and give the action base.action_partner_form and hide the current customers if needed.

You may do on interface or code level:

If code, you should fully redefine the meny unit xml in your app. E.g. for a pipeline in crm,   

<menuitem   id="crm.menu_crm_opportunities" action="crm.action_your_pipeline" parent="NEW_PAPRENT" sequence="4"/>

If on interface: go to Settings > Technical > User Interface > Menu Items > Find required and change the field 'Parent Menu' to yours. Be cautious: if you update the original app (e.g. Crm for a pipeline), parent would be changed back. Thus, it is better to use script modifications.

You can change any xml view by naming id to model_name.id:

here you need to change it as:

<menuitem id="sales_team.menu_partner_form" parent="your_parent_menu_id" action="base.action_partner_form" sequence="3"/>

You can also achieve the same if you create a new menu item and give the action base.action_partner_form and hide the current customers if needed.

Actuallly the best way to do this is by replacing the parent of the original view by your new id.

Example: Open a folder --> create a file.xml, __manifest__.py, __ini__.py

In your file.xml add the following

<?xml version="1.0" encoding="UTF-8"?>

<odoo>

    <data>

        <!--<record id ="property_sales_menu" model ="ir.ui.view">  -->

            <menuitem id="property_sales_menu_root"                 action="sales_team.crm_team_salesteams_act" sequence="5" name="Property Sales"/>

              <menuitem id="property_sales_menu_sub" parent ="property_sales_menu_root" sequence="1" name="Property Sales"/>