Deprecated rel_link Tags in WP Head

The following link tags were dropped in WordPress version 3.3.0

'index_rel_link' was dropped WP version 3.3.0.
'parent_post_rel_link' was dropped WP version 3.3.0.
'start_post_rel_link' was dropped WP version 3.3.0.

This means you should remove the following lines from your functions because they are not doing anything besides wasting space.

// These link rel tags were dropped in WP version 3.3.0
remove_action( 'wp_head', 'index_rel_link' );// not needed since WP 3.3.0
remove_action( 'wp_head', 'parent_post_rel_link', 10, 0 );// not needed since WP 3.3.0
remove_action( 'wp_head', 'start_post_rel_link', 10, 0 );// not needed since WP 3.3.0

See Remove Unwanted Links and Tags From WordPress Head for the useful code to remove rel links from your head.