Assuming you are referring to SharePoint 2007 here...
Just to be clear, you aren't talking about InfoPath in this case, right? Also, you aren't referring to Views, but rather you don't want people to see this field in your list forms, or do you just not want this field to show in your views?
To not show it in your views is very simple - just de-select that field from all of your views.
If you mean you don't want that field to ever show again after the form is submitted, then you have a few options. You can copy the default Edit and Display forms, edit the copies, remove that whole row, then change the list associations to use your custom forms that never show that field (to anyone). If you want it to only be visible to you, then you'd need to use InfoPath instead of list forms, or you'd need to create 2 content types - one with the field and one without - then configure the list so that the initial submission uses the content type with the field, and all subsequent uses of the item use the 2nd content type. For instructions on this trick, I'll have to send one of my folks to explain it.
In 2010, this can be done more easily just as an FYI.