You can uninstall or removes an installed block-modules-4.8.0-26-powerpc package itself from Ubuntu 17.04 (Zesty Zapus) through the terminal,
$ sudo apt-get remove block-modules-4.8.0-26-powerpc
If you would like to remove block-modules-4.8.0-26-powerpc and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove block-modules-4.8.0-26-powerpc
If you use with purge options to block-modules-4.8.0-26-powerpc package all the configuration and dependent packages will be removed.
$ sudo apt-get purge block-modules-4.8.0-26-powerpc
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 block-modules-4.8.0-26-powerpc