If you want to delete an export feed, go to the Feed overview and then to the Settings tab of the feed you want to delete. Now, click on the gear icon in the top right corner and click on 'delete feed':
You then need to type in the word 'delete' and click on 'delete feed' again to confirm you really want to remove the feed:
IMPORTANT: if you remove a feed there is no way to get it back. Always double check you have the right feed, and you are sure you want to permanently remove it from your project. If you think you might need the feed again in the future, it's better to deactivate it rather than remove it.