Exclude terms from your tag and category widgets http://metinsaylan.com/wordpress/2011/06/12/how-to-exclude-categories-and-tags-from-your-widgets/

wordpress_exclude_terms.php

<?php 

function shailan_filter_terms( $exclusions, $args ){

	// IDs of terms to be excluded
	$exclude = "3,257"; // CHANGE THIS TO IDs OF YOUR TERMS

	// Generation of exclusion SQL code
	$exterms = wp_parse_id_list( $exclude );
	foreach ( $exterms as $exterm ) {
			if ( empty($exclusions) )
					$exclusions = ' AND ( t.term_id <> ' . intval($exterm) . ' ';
			else
					$exclusions .= ' AND t.term_id <> ' . intval($exterm) . ' ';
	}

	// Closing bracket
	if ( !empty($exclusions) )
		$exclusions .= ')';

	// Return our SQL statement
	return $exclusions;
}

// Finally hook up our filter
add_filter( 'list_terms_exclusions', 'shailan_filter_terms', 10, 2 );

?>