How to delete taxonomy term when a wordpress user is removed?

Replace this with yours:

add_action( 'delete_user', 'yg_user_delete', 10, 1 );

function yg_user_delete( $user_id ) {

    $user_info = get_userdata($user_id); 
    $user_name = $user_info->user_login;

    print_r($user_info);

    wp_delete_term( get_term_by('name', $user_name, 'user1')->term_id, 'user1', array() );

}