Ok i figured this out myself. I created a child theme and added a file called style.css with the code
/*
Theme Name: Nano Blogger Child
Template: nano-blogger
Version: 1.0.0
*/
@import url("../nano-blogger/style.css");
/* =Theme customisation starts here
-------------------------------------------------------------- */
#container {
width: 780px;
}
and a file called functions.php with the code
<?php
function remove_some_widgets(){
unregister_sidebar( 'primary_widget_area' );
//unregister_sidebar( 'secondary_widget_area' );
}
add_action( 'init', 'remove_some_widgets', 11 );
?>
and that’s worked.