How do I delete the date/time stamp from a photo uploaded into ibook?

Do you mean the date printed on the face of the photo? You can try using the Retouch button to get rid of the date:

Otherwise you'll need a 3rd party image editor that has the capability to do the job like the clone or healing tool in Photoshop Elements for Mac or Gimp or the Stamp tool in GraphicConverter.

The following was down with Photoshop Elements:

Assuming that you have set you camera to put a date/time on the photos you can not remove it as it is part of the photo - you can blur or obscure it using the iphoto retouch tool or with PhotoShop Elements you can use the clone tool to cover it with similar events form elsewhere in the photo

But if you do not want it in your photo then yo need to change the camera settings so that the future photos do have it

LN