$ sudo apt-get remove rdesktop 

Uninstall rdesktop including dependent package

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

$ sudo apt-get remove --auto-remove rdesktop 

Use Purging rdesktop

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

$ sudo apt-get purge rdesktop 

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 rdesktop 

See Also,