Delete all files and folders in a document library

Are you looking to delete all files and folders in a document library, look no further.

Ensure your users are empowered to do so by elevating their privilege, allow unsafe update then loop through the library in question.

SPSecurity.RunWithElevatedPrivileges(delegate()
            {
                using (SPSite elevatedSite = new SPSite(SPContext.Current.Site.ID))
                {
                    using (SPWeb web = elevatedSite.RootWeb)
                    {
                        web.AllowUnsafeUpdates = true;
                        web.ValidateFormDigest();
                        System.String listName = LibraryName;
                        SPFolderCollection folders = web.Folders[listName].SubFolders;
                            foreach (SPFolder folder in folders)
                            {
                                if (folder.Name != "Forms")
                                    web.Folders[listName].SubFolders.Delete(folder.Url);
                            }
                            web.AllowUnsafeUpdates = false;
                    }
                }
            });

QED