Deleting the Series Engine plugin is simple (not that you'll ever want to delete such a handy plugin). Before you remove the plugin from your site, be sure to export your data and settings just in case you ever need them again.
The first step in deleting the plugin is to deactivate it first.
Navigate to Plugins > Installed Plugins, scroll until you see Series Engine, and click "Deactivate." This will functionally remove Series Engine from your site, but won't delete the plugin files or remove plugin data from the database.
If you've deactivated the plugin and want to permanently delete all plugin files from your server and database, navigate to Plugins > Installed Plugins, scroll until you see Series Engine, and click "Delete."
Note: When you delete the plugin, all files, content, and settings are permanently deleted. Make sure you really want to get rid of all of that data before you click "Delete!"