Error log

How can prevent these errors from appearing in the error log file?

ERROR - 2017-08-27 09:46:37 --> 404 Page Not Found: Apple-touch-icon-precomposedpng/index
ERROR - 2017-08-27 09:46:38 --> 404 Page Not Found: Apple-touch-iconpng/index
ERROR - 2017-08-27 10:29:03 --> 404 Page Not Found:


Thanks