Bartender 3

To Remove Bartender 2 you can simply drag Bartender 2 from where you installed it to Trash.

If you want to remove all files related to Bartender 2 you will need to remove.

Bartender.app from wherever it was placed, most likely Applications.

/Library/ScriptingAdditions/BartenderHelper.osax

~/Library/Preferences/com.surteesstudios.bartender.plist

/Library/PrivilegedHelperTools/com.surteesstudios.Bartender.BartenderInstallHelper

/Library/Audio/Plug-Ins/HAL/BartenderAudioPlugIn.plugin

And if it exists:

/System/Library/ScriptingAdditions/BartenderSystemHelper.osax

Bartender will then be completely removed.