How to Disable View as Grid/List Buttons in Magento 2.1

The simplest and easiest to implement is to use the Custom Design tab for the category you want to force the grid / list view by entering the following in the Custom Layout Update:

Grid View:

<reference name="product_list_toolbar">
<action method="setData"><key>_current_grid_mode</key><value>grid</value</action>
</reference>

List View:

<reference name="product_list_toolbar">
<action method="setData"><key>_current_grid_mode</key><value>list</value></action>
</reference>

If you want to add option in the sort menu then you need to create a plugin as I achieved

1) create di.xml file and the below code

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">

<type name="Magento\Catalog\Model\Config">
        <plugin name="add_custom_sort" type="Test\MyMagento\Plugin\Catalog\CustomSort" sortOrder="10"/>
    </type>

</config>

2) create CustomSort.php file and the bleow code

<?php
namespace Test\MyMagento\Plugin\Catalog;

class CustomSort
{

    public function afterGetAttributeUsedForSortByArray(
    \Magento\Catalog\Model\Config $catalogConfig,
    $options
) {

    $options['mostviewd'] = __('Mostveiwd');
    return $options;

 }

}