Add below code snippet

function create_custom_post_type() {
    register_post_type('custom_type',
        array(
            'labels' => array(
                'name' => __('Custom Type Name'),
                'singular_name' => __('Custom Type Name')
            ),
            'public' => true,
            'has_archive' => true,
            'capability_type' => 'page', // or 'post'
            'map_meta_cap' => true,
            'capabilities' => array(
                'create_posts' => false, // Removes support for the "Add New" button
            ),
        )
    );
}
add_action('init', 'create_custom_post_type');

If you want to add more then one comman, do as shown below

function create_custom_post_type() {
    register_post_type('custom_type',
        array(
            'labels' => array(
                'name' => __('Custom Type Name'),
                'singular_name' => __('Custom Type Name')
            ),
            'public' => true,
            'has_archive' => true,
            'capability_type' => 'page', // or 'post'
            'map_meta_cap' => true,
            'capabilities' => array(
                'create_posts' => false, // Removes support for the "Add New" button
            ),
        )
    );
    register_post_type('custom_type',
        array(
            'labels' => array(
                'name' => __('Custom Type Name'),
                'singular_name' => __('Custom Type Name')
            ),
            'public' => true,
            'has_archive' => true,
            'capability_type' => 'page', // or 'post'
            'map_meta_cap' => true,
            'capabilities' => array(
                'create_posts' => false, // Removes support for the "Add New" button
            ),
        )
    );
}
add_action('init', 'create_custom_post_type');

Change custom_type to your correct slug.
Change Custom Type Name to your Post Type Name.