The TC is a network drive.. you cannot check it...
Apple provided one and only one exception to this via the airport utility.. you can erase the disk. Do a quick erase and your failed fail transfer will be deleted and you can start over.
The latest AC version TC has much less controls than previous versions so you are kind of stuck.
There are methods of deleting folders via the terminal.. i am not sure of the commands.
There might be permissions problems.
And worst of all you might have loaded the files into the sparsebundle.. which directory did you load these files into.. I hope you created a new folder under Data share. If you loaded it into sparsebundle it cannot be deleted. You have a permissions issue.
There is a trick suggested in this post.. to create an empty folder.. with the same name as the problem folder.. that really should not work or even be possible.. but it could work for you.
https://discussions.apple.com/thread/5284123?answerId=22895031022#22895031022