$ sudo apt-get remove gretl-doc 

Uninstall gretl-doc including dependent package

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

$ sudo apt-get remove --auto-remove gretl-doc 

Use Purging gretl-doc

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

$ sudo apt-get purge gretl-doc 

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 gretl-doc 

See Also,