You can uninstall or removes an installed evolution-data-server-online-a package itself from Ubuntu 16.04 LTS (Xenial Xerus) through the terminal,
$ sudo apt-get remove evolution-data-server-online-a
If you would like to remove evolution-data-server-online-a and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove evolution-data-server-online-a
If you use with purge options to evolution-data-server-online-a package all the configuration and dependent packages will be removed.
$ sudo apt-get purge evolution-data-server-online-a
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 evolution-data-server-online-a