How to remove this from WP head:
<link rel='dns-prefetch' href='//maps.google.com'>
I had this also:
<link rel='dns-prefetch' href='//s.w.org'>
But, I removed it with this code inside my functions.php
add_filter( 'emoji_svg_url', '__return_false' );
Probably, this is added by one plugin exifografy, which can show map of location where image is taken. But, there is just few posts with map, so having this on all URL-s is just one more line of not used HTML code.