Is it possible to delete a post, and or an attachment to that post? I have made a mistake in one of my attachments, and would like to delete it! (specifically, my post about the OSM import/export script, i forgot to delete my login details from the script !!!)

Check out the Manifold Wiki with SQL and scripting examples at http://www.manipedia.eu/

I think you'll have to contact tech@manifold.net and make a special request, as usually, no - you can only edit the post for 15 minutes.

i think all users website ( blog forum comment) don't respect privacy since people can post but can't control their post ( remove modify ) or destroy modify their account.

When a lot of people have taken notice of a posting I think it's no longer a term of privacy of the author only to have the posting frozen in public. You'r free to correct your statements in public with a second posting. A bit annoing for readers and awkward for yours and mine typos in a foreign language but good style for a responsible communication.

For me this is different in petzlux case of an author correcting his erroneous attachments. These usually are code only visited by readers with special interest in the topic and it leads to hassle not to have them corrected and the wrong version deleted. So dropping the old version usually comes with a request to download the update but there is no use in keeping the old one in public.

why not to be able to delete only our own post that have no reply or only replies by the people who post first .... ( in many case mean the question is too simple , show user don't take time to work on the subject before post ) . i must be one of the manifold user in forum that have the more post with no reply ....It disturb me .

Any form of rewriting history is a potential for abuse. Better play it safe. Posts with trivial questions do no harm.