Exclude Tags from Posts page

Some users would like to exclude certain tags from the posts page. This can be done with the following PHP snippet:

function exclude_posts( $query ) { 
    if ( $query->is_home() ) {  
        $query->set( 'tag__not_in', array( 13 , 26 ) ); 
    } 
} 
add_action( 'pre_get_posts', 'exclude_posts' );

Simply edit your tag IDs in there instead of the 13 and 26 (examples).