To delete a head you've already made, just go to the 'My Heads' section of your 'My Account' page:

http://sendables.jibjab.com/my_account/my_heads

 You can then either edit the information about the head or remove it altogether.

We apologize, but there is no way to edit the shape of a head that you've already prepared. You will need to re-upload and recut the head if you wish to re-shape it.

In addition, any head you remove will still appear in any eCard you made with it, so you will need to remove the eCard itself if you no longer want it to appear.