If you have been made into a moderator for a Google+ Community, you can remove posts, pin them so that they appear at the top of the community page, and view more information about the activity history of the author in the community.

To edit a post, click on the menu icon in the upper-right corner of the post.

This will give you a number of options - to remove the post in question, to ban the member who posted it, to pin it to the top of the community, etc.