Yes you are able to get feedback to sites that confirm to guidelines and not just blatant self promotion.
Posts can be edited and deleted within a timeframe of about an hour and then they are locked. Approved requests to Moderators will enable post changes.
Editing previous posts in a Topic can make nonsensical replies. It is best to quote text from a previous reply in case the previous reply was edited.
Please give examples of why you would want to delete replies to your posts.
Edit:
As an example this post has been edited and revisions maybe seen by clicking the top right pencil icon
You may ask for a site review. The guidelines are in the FAQs.
As @John_Betong says, there is an edit window (5 hours, I believe), after which only moderators can edit a post.
You can delete your own posts within the edit window, unless it is the opening post of a topic. We do not generally delete topics where there have been responses made, but may do so in exceptional circumstances. However, it is safer not to post anything you don’t want to become public, as these forums are crawled and indexed by search engines.
I suggest you read the FAQs for more information about the forums.
I’ve always thought it was a good idea to read a forum’s rules/FAQ before signing up, to make sure I understand what’s allowed and what’s expected of me.
It’s surprising how many people seem not to do that.