Storage limits

What are the album names ? Albums that are created by the app itself (e.g. Panoramas, Screenshots) will (or should) disappear if they are empty.

Albums that you created yourself don't take up much space, they effectively only create pointers to the photos that you put in them, not separate copies of the photos.

What are the albums i.e. are they built-in albums, albums that you've created directly on the iPad, or albums synced from a computer ? Albums synced from a computer can't be deleted directly on a device, they are deleted by re-connecting to your computer's iTunes, changing your sync selected, and re-syncing.

If they were created on the iPad you should be able to delete them (built-in albums e.g. Camera Roll, Panoramas can't be deleted, thought if empty they should disappear), it's albums that were synced from a computer that can't be deleted directly in Photos

1. Album created on your iPad from photos in the Camera Roll album can be deleted directly on the iPad. But that only deletes an alias to the photo stored in the Camera Roll album. To actually delete those photos you need to delete the photos from the Camera Roll album.

Photos deleted from the Camera Roll album and not immediately deleted. They are moved to the Recently Deleted album where they can reside for 30 days should you want to recover them. If you want to delete those photos permanently to free up space on the iPad then delete them again from the Recently Deleted album.

2. Photos in albums that were synced from your computer using iTunes on the computer are removed by doing another sync with the computer. Connect your iPad to the computer, select your iPad in iTunes on the computer, then deselect the unrated albums in iTunes. When you click on Sync in iTunes the albums will be removed from your iPad and they will remain on your computer.