I used CCleaner to find duplicate files on my HDD. Once it came up with a list of duplicates, how do I decide which files to delete? If I delete all of the files in the list, are the original files still on the computer or do I have to leave one to not be deleted? Can I do a bulk selection or do I have to select each file individually? Thanks.
You have to select the files yourself. This is deliberate.
Some system and other program files need to have duplicates for things to work properly.
So unless you are very tech savvy you should leave those alone and only look at your own files - documents, photos, videos, and the like.
While CCleaner can find duplicates for you only you can decide which to keep or not.
You wouldn't like it if a programme deleted the wrong thing.