You can uninstall or removes an installed bandwidthd-pgsql package itself from Ubuntu 16.10 (Yakkety Yak) through the terminal,
$ sudo apt-get remove bandwidthd-pgsql
If you would like to remove bandwidthd-pgsql and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove bandwidthd-pgsql
If you use with purge options to bandwidthd-pgsql package all the configuration and dependent packages will be removed.
$ sudo apt-get purge bandwidthd-pgsql
If you use purge options along with auto remove, will be removed everything regarding the package, It's really useful when you want to reinstall again.
$ sudo apt-get purge --auto-remove bandwidthd-pgsql