I would probably do it the old-fashioned way myself - I wouldn't trust a program to delete any of my precious photos without my okay on each one!
Interestingly, in all the "declutter your life" articles that one reads in the new year, I read one about decluttering your photos. With digital photos, we take so many just because we can - but not all of them are very good, and the best ones are buried in the "clutter" of all the mediocre and just plain bad ones. Think about how many photos you have taken and will continue to take in your lifetime - and what you will leave behind someday for someone else to deal with. If it's a chore for you to find the gems in your files, think what it will be like for someone else!
The article I read recommended going through and culling out the best ones and just dumping the rest. I'm not sure I could dump any yet (I'll admit, I'm a photo hoarder), but I do plan to go through and put my "best" photos in a separate folder within a folder for each date or event, i.e., 2016 Dec Christmas for a main folder and 2016 Dec Christmas Best for the ones that "make the cut." The goal would be to eventually edit, crop and print out those best photos for albums or photobooks or use them to scrap. (Maybe I'm a little OCD, but I make a folder inside that one for edits, because I never save over my original photo.) Before I get ready to print or use them, I will look at the main folder again just to make sure there are not any I left in there that I really want, and if not, I guess I will bring myself to delete them at that point.
It is a really overwhelming task, especially if you haven't been using some type of a folder system to store them, but if you have a laptop that you use at night while watching TV, you could devote 15-20 minutes to it every couple of nights consistently and you will eventually eat that elephant!