sudo dpkg -r tzdata
dpkg: dependency problems prevent removal of tzdata:
 ubuntu-minimal depends on tzdata.
 util-linux depends on tzdata (>= 2006c-2).
 postgresql-9.3 depends on tzdata.
 python-dateutil depends on tzdata.
 libtcl8.5:amd64 depends on tzdata.
 libtcl8.6:amd64 depends on tzdata.
 python3-dateutil depends on tzdata.
 libical1 depends on tzdata.
 python-tz depends on tzdata.

dpkg: error processing package tzdata (--remove):
 dependency problems - not removing
Errors were encountered while processing:
 tzdata