You can uninstall or removes an installed m4 package itself from Ubuntu 14.04 LTS (Trusty Tahr) through the terminal,
$ sudo apt-get remove m4
If you would like to remove m4 and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove m4
If you use with purge options to m4 package all the configuration and dependent packages will be removed.
$ sudo apt-get purge m4
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 m4
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