Simple snippet for adding a checkbox to hide widgets from logged in users

hide-widget-from-logged-in-users.php

<?php 

// Widget form

function cust_widget_form( $widget, $return, $instance ) {

	if( ! isset( $instance['logged_out_only'] ) ) {
		$instance['logged_out_only'] = false;
	} ?>

	<p>
		<input name="<?php echo $widget->get_field_name('logged_out_only'); ?>" type="checkbox" value="1" <?php checked( $instance['logged_out_only'], 1 ); ?> />
		<label>Hide from logged in users</label>
	</p>

	<?php

}

add_action( 'in_widget_form', 'cust_widget_form', 10, 3 );

// Save widget

add_filter( 'widget_update_callback', function( $instance, $new_instance ) {

	if( isset( $new_instance['logged_out_only'] ) ) {
		$instance['logged_out_only'] = $new_instance['logged_out_only'];
	} else {
		unset( $instance['logged_out_only'] );
	}

	return $instance;

}, 10, 2 );

// Hide widget

add_filter( 'widget_display_callback', function( $instance ) {

	if ( ! empty( $instance['logged_out_only'] ) && is_user_logged_in() ) {
		return false;
	}

	return $instance;

} );