Your cannot edit any of your posts, a main reason for this is people will lie and manipulate the privilege in an abusive manner. You can delete other users post on your profile as inevitably it is your profile page. Although, staff members can still see any posts you have deleted and why you have deleted them, which is easy to moderate. If you find it necessary for your post/thread to be edited, please contact a staff member, we will be more than happy to assist you. :)