Since I don't use unity, why I cannot remove libunity9 package in Xubuntu?
Remove this package will also remove many software such as: brasero, shotwell and usb-creator-gtk
$ sudo apt-get remove libunity9
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
libraw5 brasero-common libunique-3.0-0 libgexiv2-1 dvd+rw-tools librest-0.7-0 libtotem-plparser17 libquvi-scripts
libgmime-2.6-0 growisofs libquvi7
Use 'apt-get autoremove' to remove them.
The following packages will be REMOVED:
brasero brasero-cdrkit gir1.2-unity-5.0 libbrasero-media3-1 libunity9 shotwell usb-creator-gtk
0 upgraded, 0 newly installed, 7 to remove and 0 not upgraded.
After this operation, 11.4 MB disk space will be freed.
Do you want to continue [Y/n]?