After upgrading to Mac OS High Sierra, you probably get some built in app is running when your mac is used. This simple tutorial will get you how to turn off built in apache server on Mac OS High Sierra 10.13.

Open terminal and type this to unload Apache Server startup:

sudo launchctl unload -w /System/Library/LaunchDaemons/org.apache.httpd.plist

type your sudo password and press enter button. The built in apache should stopped and never starting again.