Copy and paste the following code in your child theme’s functions.php file.

Adding new field in package table

add_filter( 'wpcargo_package_fields', 'wpcargo_package_add_fields_callback' );
function wpcargo_package_add_fields_callback( $package_fields){
  //Add fields
  $package_fields['new_field_1'] = array(
    'label' => __('New Field 1', 'wpcargo'),
    'field' => 'text',
    'required' => false,
    'options' => array()
  );
  $package_fields['new_field_2'] = array(
    'label' => __('New Field 2', 'wpcargo'),
    'field' => 'text',
    'required' => false,
    'options' => array()
  );  
  return $package_fields;
}

Make fields required.

add_filter( 'wpcargo_package_fields', 'wcp_custom_wpcargo_package_fields', 10, 1 );
function wcp_custom_wpcargo_package_fields( $package_fields ){
    /* Change fields to text */
    $package_fields['wpc-pm-qty']['required'] = true;
    $package_fields['wpc-pm-piece-type']['required'] = true;
    $package_fields['wpc-pm-description']['required'] = true;
    $package_fields['wpc-pm-length']['required'] = true;
    $package_fields['wpc-pm-width']['required'] = true;
    $package_fields['wpc-pm-height']['required'] = true;
    $package_fields['wpc-pm-weight']['required'] = true;
    return $package_fields;
}

Allow fields accepts decimal value.

add_filter( 'wpcargo_package_fields', 'wcp_custom_wpcargo_package_fields', 10, 1 );
function wcp_custom_wpcargo_package_fields( $package_fields ){
    /* Change fields to text */
    $package_fields['wpc-pm-qty']['field'] = 'text';
    $package_fields['wpc-pm-piece-type']['field'] = 'text';
    $package_fields['wpc-pm-description']['field'] = 'text';
    $package_fields['wpc-pm-length']['field'] = 'text';
    $package_fields['wpc-pm-width']['field'] = 'text';
    $package_fields['wpc-pm-height']['field'] = 'text';
    $package_fields['wpc-pm-weight']['field'] = 'text';
    return $package_fields;
}

Removing of fields.

In default these are the availble fields:

• wpc-pm-qty
• wpc-pm-piece-type
• wpc-pm-description
• wpc-pm-length
• wpc-pm-width
• wpc-pm-height
• wpc-pm-weight
• unit-price
• unit-amount

add_filter( 'wpcargo_package_fields', 'modify_package_fields' );
function modify_package_fields( $package_fields){
	/*
	 * Removing the Description in package table
	 * Just put the package field name like "wpc-pm-description"
	 * Can remove also the other fields 
	 */
	unset( $package_fields['wpc-pm-description'] );
	return $package_fields;
}