How to unsubscribe a BulkFileListener

I registered one like this:

ApplicationManager.getApplication().getMessageBus().connect(project).subscribe(VFS_CHANGES, new ConfigBulkFileListener());

ConfigBulkFileListener is my implementation of BulkFileListener.

But how can I unsubscribe the listener? I tried:

ApplicationManager.getApplication().getMessageBus().connect(project).disconnect();
ApplicationManager.getApplication().getMessageBus().connect(project).subscribe(VFS_CHANGES, null);

both don't work, my listener still get triggered.

Thanks.