$ sudo apt-get remove libapt-pkg4.12 

Uninstall libapt-pkg4.12 including dependent package

If you would like to remove libapt-pkg4.12 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove libapt-pkg4.12 

Use Purging libapt-pkg4.12

If you use with purge options to libapt-pkg4.12 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge libapt-pkg4.12 

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 libapt-pkg4.12 

See Also,