How to stop autosuggest in node author field and write our own? Is there anyway to stopping auto suggest in author field of node content and write our own author names instead of users??
You could write a small module that implements hook_form_alter in which you remove the autocomplete functionality for this field.  This should convert it to a textfield.  However, this will certainly break if an author name that is not also the username of a user is inserted, since this field is used to populate $node->uid, which must have a valid username.

A more viable solution would be to create a vocabulary of your author names, and a taxonomy term field on your content type (pointing at that vocabulary).  And then display this field as you desire.