Nuke is a reverse engineered version of the extension with the same name, which is used to mass delete pages from a user's contributions or recent changes. As with all deletion of pages, it requires administrator rights to use. You can access Nuke via any user's contributions page, or Special:Specialpages. It is possible to use this version of Nuke whilst already having access to the extension.
To change the default delete reason, add the following variable above the import:
nukeDeleteReason = "Cleanup";