I have noticed a lot of plugins over the years lack the ability to totally uninstall files. What I mean by totally uninstalling is that when you use your WordPress admin panel to delete the files, it does not always take away the database tables that were installed in the beginning. A couple I can think of up front, are Next Gen Gallery and WP Link Directory.

While it might not seem so important for most people, it is important to remove any resources that you do not plan to use on your webhosting space because it could prove to be a way to hack into later on in the future. If hacked, this can run up your resources and suspend, or with some webhosts, they may ask you to upgrade or say they cannot host you.

Also, when you are having some issues with installing a plugin, you may need to uninstall before going back to re-install. Those databases might be conflicting with what you are trying to re-install. It is usually something the plugin author may ask you to do alongside clearing your cache.

These also take up unnecessary space.

As much as you could download a database manager plugin, or Clean Options, a plugin to clean up your MySQL database tables for your WordPress. The problem is, you really do not need to install another plugin to remove plugins. It is unnecessary because it is easy to do.

For those with phpmyadmin, you can simply go in, browse your WordPress database, and look for the tables that reflect the plugins you removed from the front end. A lot of times, plugin creators try to name their database tables as close as possible to the plugin that they can. Just checkmark, select drop, and click the submit (‘go’) button. Presto! They are removed.