You have set up albums on the iPad and now you want to delete the photos from the camera roll. You can't do that.
When you create albums in the Photos app, those albums do not contain copies of the photos from the camera roll - but merely pointers to those photos. Albums created on the iPad are for local storage and organization only. Those albums will not import to your computer either since there really are no photos in them.
So ... If you try to delete the photos from the camera roll - it will be deleted in all of the albums that the photo is in on the iPad photos app.