$ sudo apt-get remove libsaga 

Uninstall libsaga including dependent package

If you would like to remove libsaga and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove libsaga 

Use Purging libsaga

If you use with purge options to libsaga package all the configuration and dependent packages will be removed.

$ sudo apt-get purge libsaga 

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 libsaga 

See Also,