How did the photos get on the iPad ? You should be able to delete photos that were taken with the iPad, copied onto it via the camera connection kit, or saved from emails/websites etc 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 and selecting the photos if 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. To delete all synced photos you can select and sync just an empty folder on the Photos tab, or you might also be able to do it via Settings > General > Usage > Photos & Camera (under 'Storage') and swipe across the 'Photo Library' line - that should get a Delete button to appear .
The links below have instructions for deleting photos.
iOS and iPod: Syncing photos using iTunes
iPad Tip: How to Delete Photos from Your iPad in the Photos App
Another Way to Quickly Delete Photos from Your iPad (Mac Only)
How to Delete Photos from iPad
iPhoto for iOS (iPad): Delete photos from iPhoto
How to: Batch Delete Photos on the iPad
(With iOS 5.1, use 2 fingers)
How to Delete Photos from iCloud’s Photo Stream
How much space is used by your Other? You may be able to reduce.
How Do I Get Rid Of The “Other” Data Stored On My iPad Or iPhone?
With an iOS device, the “Other” space in iTunes is used to store things like documents, settings, caches, and a few other important items. If you sync lots of documents to apps like GoodReader, DropCopy, or anything else that reads external files, your storage use can skyrocket. With iOS 5/6, you can see exactly which applications are taking up the most space. Just head to Settings > General > Usage, and tap the button labeled Show All Apps. The storage section will show you the app and how much storage space it is taking up. Tap on the app name to get a description of the additional storage space being used by the app’s documents and data. You can remove the storage-hogging application and all of its data directly from this screen, or manually remove the data by opening the app. Some applications, especially those designed by Apple, will allow you to remove stored data by swiping from left to right on the item to reveal a Delete button.