Neos\Neos\Controller\Module\Management\WorkspacesController::discardNodeAction PHP Method

    public function discardNodeAction(NodeInterface $node, Workspace $selectedWorkspace)
    {
        // Hint: we cannot use $node->remove() here, as this removes the node recursively (but we just want to *discard changes*)
        $this->publishingService->discardNode($node);
        $this->addFlashMessage($this->translator->translateById('workspaces.selectedChangeHasBeenDiscarded', [], null, null, 'Modules', 'Neos.Neos'));
        $this->redirect('show', null, null, ['workspace' => $selectedWorkspace]);
    }