As Yer_Man says, views like Recents and Imports and Library are provided to present all the pictures in an order that never changes, so every phone every time every where can be counted on to do the same thing.
By the way, "album" and "folder" mean different things-- folders can contain albums and other folders but not pictures; albums contain pictures. I have folders of a trip, for instance, that contain albums for each day.
But deleting foldrers and albums is the same: control click on the album or folder to get a menu, and chose Delete.

Deleting an album will remove the album, but the pictures remain in the Library. Albums are just lists-- they list the pictures you'd like to see together. So deleting a list doesn't delete the picture--pictures listed in other albums will not be disturbed.
Folders are a bit different-- if you delete a folder, then all the album lists inside will also be deleted. Again, the pictures themselves won't affected.
To delete a picture from the Library, you can use command-delete. The picture is then listed in Recently Deleted for 30 days to give you a chance to change your mind.