In this guide I will teach you how to appear offline on your battle.net account so you can hide from friends whilst botting, or if you just don't want to talk.
Open up your firewall (I'm using just the usual Windows firewall).
Create a new OUTBOUND rule.
Make it a port rule, not a program.
The port required is 1119 (TCP).
Block that port.
Keep clicking next if you're on windows firewall client, and just click finish.
Note: You cannot login to WoW if you have this rule enabled, so disable the rule first then once you have logged into the game, enable it, and it will log you out of battle.net but keep you in World of Warcraft.