I have an ubuntu-Mate-based desktop, which I "upgraded" to kde neon and have been playing with for a couple of months.
I now wish to "upgrade" my installation to ubuntu-mate -- switching distribution from kde neon"
FYI
cat /etc/os-release
NAME="KDE neon"
VERSION="16.04 LTS"
ID=neon
ID_LIKE=ubuntu debian
PRETTY_NAME="KDE neon Developer Edition on 16.04 LTS"
VERSION_ID="16.04"
HOME_URL="http://neon.kde.org/"
SUPPORT_URL="http://neon.kde.org/"
BUG_REPORT_URL="http://bugs.kde.org/"
UBUNTU_CODENAME=xenial
Hi,
I assume you had Ubuntu Mate installed before KDE Neon, can you just not simply remove the KDE Neon package(s) ?.
I personally would recommend a full install of UM 16.04 wiping both home and root and start afresh!. 
thanks wolman.
Yes, i added neon repos to my apt sources.
i’m loathe to fully wipe because i’m running on zfs
so, I’ll try removing neon first
cheers
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Hi,
if you have Ubuntu Mate as your base system then remove the KDE Neon PPA as you already suggest and if it is a meta package, remove the offending package, that way you won’t have to do a fresh install!. 
This is a ppa install?
What about using ppa-purge?
http://manpages.ubuntu.com/manpages/xenial/man1/ppa-purge.1.html
I prefer the terminal, but you can add a excellent GUI, “y-ppa-purge”.
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