Pause Host and HTML engines and stop the web server in ADGate. Quit ADGate. Move it to the trash, empty it and make sure nothing is left there. Copy the new version of ADGate to disk. Start it and fill in your admin password.
That is all.

This problem is fixed in version 3.2.0.
A bug in the registration code makes ADGate match all DNS lookups to localhost, if and only if pirated serie numbers are used. To fix this, quit ADGate and remove com.li.hao.adhelper.plist in your home/Preferences folder and restart.

In unregistered version, you cannot add or remove URL and Host patterns, so on some sites, you may notice no or few changes. You can go to http://www.macsurfer.com to check the effects by turn on and off engines in ADGate and refresh the page in browser.

Shortly, check ADGate Help from ADGate menu. You will find details there about how to remove it with or without restart.
But some users say ADGate blocks legitimate pop-ups or some sites they want to visit, so they do not want ADGate. In such case, I think one needs first try to pause engines from ADGate Preferences or Dock Menu, then reload the page in browser to see if you get them back. Turn on ADGate engines only when you are irritated by banners or pop-ups.
ADGate can be turned off with single click, and it does require some configuration works from user side to do it work in user's way.