How to hide subpanel (create and select) as well as Action buttons

Hi Team,

I am using SugarCRM version 8.1.0,

I have created two custom subpanels of Calls and Meetings(as per my requirement) in the Accounts module.

I want to hide it's (create and select) as well as Action buttons. I have made the following changes in subpanel files but it did not work for me.

custom/Extension/modules/Accounts/Ext/Layoutdefs/accounts_calls_1_Accounts.php

custom/Extension/modules/Accounts/Ext/Layoutdefs/accounts_meetings_1_Accounts.php

For Calls 
<?php
 // created: 2018-09-28 06:38:31
$layout_defs["Accounts"]["subpanel_setup"]['accounts_calls_1'] = array (
 'order' => 100,
 'module' => 'Calls',
 'subpanel_name' => 'default',
 'sort_order' => 'asc',
 'sort_by' => 'id',
 'title_key' => 'LBL_ACCOUNTS_CALLS_1_FROM_CALLS_TITLE',
 'get_subpanel_data' => 'accounts_calls_1',
 'top_buttons' => 
 array (
 0 => 
 array (
 'widget_class' => '',
 ),
 1 => 
 array (
 'widget_class' => '',
 'mode' => 'MultiSelect',
 ),
 ),
);

For Meetings

<?php
$layout_defs["Accounts"]["subpanel_setup"]['accounts_meetings_1'] = array (
 'order' => 100,
 'module' => 'Meetings',
 'subpanel_name' => 'default',
 'sort_order' => 'asc',
 'sort_by' => 'id',
 'title_key' => 'LBL_ACCOUNTS_MEETINGS_1_FROM_MEETINGS_TITLE',
 'get_subpanel_data' => 'accounts_meetings_1',
 'top_buttons' => 
 array (
    0 => 
    array (
       'widget_class' => '',
    ),
    1 => 
    array (
       'widget_class' => '',
       'mode' => 'MultiSelect',
       ),
    ),
);


As shown above i have removed the widget_class for both subpanel but still "Action" buttons and create and select
Buttons showing on subpanel top.

Please suggest ?

Thanks,
Rupesh Ranjangaonkar