How to upgrade in place from 16.10 unity to 17.04 gnome

[Pander]

To remove Unity, I simply use dpkg -P packagenames. When that list becomes long from many dependencies, I put the output of that through grep to get all the depending packages and cat those to a file. Edit the file (vim and a lot of Shift-j) and put dpkg -P at the beginning. I use the same trick for ouput of dpkg -l|grep -v ^ii

Of course, check if those lists of package names are okay to purge before doing bulk purges. Some packages are tricky, see my post a while back on Unity dependencies.