Deleting photos from my IPad Air

I imported some random photos from my desktop computer to test the photo import option on my new IPad Air. These photos are visible when I click on My Photos on the main menu screen, along with photos taken with the IPad, but are not visible when I click on my Photo Booth, which seems to store only pics. taken with my IPad. I want to delete the photos imported as a test but when I select them in My Photos the option to delete them (the dustbin) does not light up as an option. How can I delete them? Any help appreciated.