SF_10.1, SF_10.2, SF_11.0, SF_11.1, SF_11.2, SF_12.0, SF_12.1, SF_12.2, SF_13.0, SF_13.1, SF_13.2, SF_13.3, SF_14.0, SF_14.1, SF_14.2, SF_14.3 - https://docs.sitefinity.com/for-developers-delete-document-libraries

DeleteLibraryNativeAPI.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Telerik.Sitefinity.Libraries.Model;
using Telerik.Sitefinity.Modules.Libraries;

namespace Telerik.Sitefinity.Documentation.CodeSnippets.DevGuide.SitefinityEssentials.Modules.MediaModules.DocumentsAndFiles.ManagingLibraries
{
    public partial class LibrariesSnippets
    {
        private void DeleteDocumentLibraryNativeAPI(Guid documentLibraryId)
        {
            LibrariesManager manager = LibrariesManager.GetManager();

            DocumentLibrary library = manager.GetDocumentLibraries().Where(b => b.Id == documentLibraryId).SingleOrDefault();

            if (library != null)
            {
                //Mark the library to be deleted.
                manager.DeleteDocumentLibrary(library);

                //Save the changes.
                manager.SaveChanges();
            }
        }
    }
}