You can uninstall or removes an installed libjs-less package itself from Debian 8 (Jessie) through the terminal,
$ sudo apt-get remove libjs-less
If you would like to remove libjs-less and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove libjs-less
If you use with purge options to libjs-less package all the configuration and dependent packages will be removed.
$ sudo apt-get purge libjs-less
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 libjs-less