To delete comments you've made on a post in a pod:
On the discussion post you'd like to delete your comment on, click on the icon shown below.
Example view of a discussion post
Then the comments for that discussion post will pop up, similar to what's shown below. You will Tap & Hold your comment on the post. You'll then be presented with the 5 options shown below. 'Copy, Look up, Share..., Edit, Delete'. Tap on 'Delete'.
*Note: You can alternatively tap 'Edit' to modify your comment.