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
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 you delete photos depends on how you got the photo to the iPad.
Daniel's suggestions work for photos obtained on the iPad either via a copy, email or taking the photo with the iPads camera.
For photos that you synced from your computer you need to go through another sync process.
Start iTunes on your computer and connect your iPad. In the left column of iTunes select your iPad. In the right column select photos. Deselect any albums you want to delete.
To delete individual photos you need to move those photos out of the synced album in iPhoto on your mac or the folder on you PC before you do the sync I described above.
I have tried the above and cannot get a delete box to appear. When I follow the directions for the camera roll and hit the arrow box a drop down appears with the following,
Assign to Contact
Use as Wallpaper
at no point does Delete appear.
Accessing some of my albums doesn't even allow that response. Please HELP!
I have an iPad2 and this is very frustrating for me because I loaded on thousands of photos using the camera connection kit, and now that I've transferred them to my home computer I want them off my iPad. I've figured out two ways to delete these photos.
In thumbnail view, I press the box and arrow icon, and a red delete button appears. Then I select each thumbnail I want to delete and press the delete button, then select 'delete everywhere'.
Or, in full screen view, I select the trash can in the top right hand corner, then select 'delete everywhere'.
This is going to take hours to do, and I will NEVER EVER use the camera connection kit for a lot of photos again!
Apple, c'mon, all we need is a "select all" button on the next software update!!