To uninstall the Compilatio plugin, you must go to "Site Administration"> "Plugins"> "Plugins overview". In the "Plagiarism Plugins" section, click on the "Uninstall" link next to "Compilatio Plagiarism Plugin".
Then click "Continue" to confirm deletion of the plugin. Note, this operation is irreversible. All Compilatio tables will be deleted, and no data can be recovered later.