how do i delete photos from my ipad

Only photos taken with the iPad, copied onto it via the camera connection kit, or saved from emails/websites etc can be deleted directly on the iPad - either via the trashcan icon in the top right corner if viewing the photo in full screen, or via the Edit button top right in thumbnail view.

Photos that were synced from your computer are deleted by moving/removing/de-selecting them from where they were synced from on your computer and then re-syncing