I have been using various devices for home media center and ATV2 is one of the devices that I own.
It has been a while since I have been using XBMC on ATV2 and today, I decided to upgrade it with Kodi.
Instead of upgrade, I have chosen to remove previous installation of XBMC and going with the clean installation of Kodi 14.x
Here is the instruction on how to remove XBMC completely from ATV2:
apt-get remove org.xmbc.xbmc-atv2
apt-get autoremove
rm -fR /private/var/mobile/Library/Preferences/XBMC
rm -fR /private /var/stash/Applications/XBMC.frappliance