To hide remove button on the item sublist and disable a field.

To hide “REMOVE button” on the item sublist

        jQuery('#item_remove').hide();      // to hide remove button

To unhide “REMOVE button” on the item sublist

        jQuery('#item_remove').show();      // to unhide remove button

To disable a field in a sales order (variable_name is variable into which the value of the required field is get.)

        variable_name.isDisabled = true;    // to disable CLOSED field

To enable a field in a sales order.

        variable_name.isDisabled = false;   // to enable CLOSED field