Theres two photo albums that are full of photos on my iphone and i want to delete them all but it wont let me it just comes up with add to! How do i go about deleting them ?

Theres two photo albums on my iphone that are full of photos and it wont let me delete the albums or any of the individual photos, i really want and need to get rid of these photos but the delte button goes blank and it only lets me click add two? please can someone help me and tell me how i can delete these albums?