core/src/main/java/com/orientechnologies/orient/core/storage/index/sbtreebonsai/local/OSBTreeBonsaiLocal.java
@Override
  public void delete() throws IOException {
    boolean rollback = false;
    final OAtomicOperation atomicOperation = startAtomicOperation(false);
    try {
      final Lock lock = FILE_LOCK_MANAGER.acquireExclusiveLock(fileId);
      try {
        final Queue<OBonsaiBucketPointer> subTreesToDelete = new LinkedList<>();
        subTreesToDelete.add(rootBucketPointer);
        recycleSubTrees(subTreesToDelete, atomicOperation);
      } finally {
        lock.unlock();
      }
    } catch (final Exception e) {
      rollback = true;
      throw e;
    } finally {
      endAtomicOperation(rollback);
    }
  }
@Override
  public void delete() throws IOException {
    boolean rollback = false;
    final OAtomicOperation atomicOperation = startAtomicOperation(false);
    try {
      final Lock lock = FILE_LOCK_MANAGER.acquireExclusiveLock(fileId);
      try {
        final Queue<OBonsaiBucketPointer> subTreesToDelete = new LinkedList<>();
        subTreesToDelete.add(rootBucketPointer);
        recycleSubTrees(subTreesToDelete, atomicOperation);
      } finally {
        lock.unlock();
      }
    } catch (final Exception e) {
      rollback = true;
      throw e;
    } finally {
      endAtomicOperation(rollback);
    }
  }
Deletes a whole tree. Puts all its pages to free list for further reusage.