
Sometimes you are posting compulsively until you post something you regret later so you want to delete it, but sadly you can't. Since blockchain is immutable you can't delete a post once it is created, but you can edit it for a limited (one week) time only. One method to edit the post you intend to delete is to clear the content and change the title to [Deleted].
Below is a step-by-step guide on how to do it:
1.Select the Post you wish to delete

Make sure the selected post is not 7 days old
2.Select 'Edit' at the bottom of your Post

3.Edit your Post title to [Deleted] and the content to [Empty]

4.Finally, select UPDATE POST.

If your feed is like this, then you are done.
So be careful with what you post, a downvote by people with large Steem Power hurts a lot. I only realized this until I got one single downvote which worth -100% of steem rewards. Luckily I found out how to edit my post few days before my reward payment.
Checkout http://www.steemd.com to explore the Steem Blockchain and http://www.steem.com/@yourusername to check your personal account or others activity in the blockchain. Checking the blockchain is a good way to make sure the update you made really got updated.