If you refer to your Boat Harbour on the site then I don't think this is possible. You can edit your original post to update the details or perhaps add that you no longer have the model. Once posted the details are shared for the benefit of all members who can discuss or comment on your post. In effect you have shared ownership and the post is protected from deletion.
Hermank's reply covers a good method to remove your model from the water, if that was your enquiry.