Comment 3 for bug 1622206

Ran into the same issue, and was stuck with apt not being able to get to a working, clean state, see below.

I had to use aptitude (instead of apt), which gave a proper solution and managed to deinstall, finally my solution was:
aptitude remove kde-telepathy-minimal
apt remove 'unity-*'
apt autoremove
apt remove kubuntu-desktop
apt install --reinstall kubuntu-desktop

# apt remove unity
Reading package lists...
Building dependency tree...
Reading state information...
Correcting dependencies... Done
The following additional packages will be installed:
  kde-config-telepathy-accounts
The following NEW packages will be installed:
  kde-config-telepathy-accounts
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
385 not fully installed or removed.
Need to get 0 B/137 kB of archives.
After this operation, 825 kB of additional disk space will be used.
(Reading database ... 55%[Y/n] (Reading database ...
(Reading database ... 759436 files and directories currently installed.)
Preparing to unpack .../kde-config-telepathy-accounts_4%3a15.12.3-0ubuntu1_amd64.deb ..
.
Unpacking kde-config-telepathy-accounts (4:15.12.3-0ubuntu1) ...
dpkg: error processing archive /var/cache/apt/archives/kde-config-telepathy-accounts_4%
3a15.12.3-0ubuntu1_amd64.deb (--unpack):
 trying to overwrite '/usr/share/accounts/services/google-im.service', which is also in
 package account-plugin-google 0.12+16.04.20160126-0ubuntu1
Processing triggers for libc-bin (2.23-0ubuntu7) ...
Errors were encountered while processing:
 /var/cache/apt/archives/kde-config-telepathy-accounts_4%3a15.12.3-0ubuntu1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

# aptitude why account-plugin-google
i unity Empfiehlt unity-scope-gdrive
i A unity-scope-gdrive Hängt ab von account-plugin-google