Hmm, I just tested a few and they all went through fine, but I do recall that sometimes there are weird edge cases that make deletion funny. Which feed are you trying to get rid of?
Okay, confirmed that the app is asking the servers to delete the feed and they are claiming it should be gone, but that it then comes back. Going to pass this off to Sam for a backend investigation.
Found the problem. Will get a fix going as soon as possible. In the mean time, you should be able to delete that feed from the website UI with no problems.