$ sudo apt-get remove libktnef4 

Uninstall libktnef4 including dependent package

If you would like to remove libktnef4 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove libktnef4 

Use Purging libktnef4

If you use with purge options to libktnef4 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge libktnef4 

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 libktnef4 

See Also,