Thanks to everyone that responded all with great idea ideas! My problem is I had 90,000 photos in my collection all neatly sorted under around 20 main topics such as family, vacations, band, etc. , and inside each one of these folders was another layer of folders and or albums such as Lake Tahoe, trip, etc.
I have a couple of western digital 4 TB backup drives that I use as an archive. I did not have enough free space on my iMac to do it from there (which would have been preferable) so I duplicated a copy of my photos library which was 600 GB onto one of the drives. After listening to everyone's advice and reading a bunch of other posts, what seems to be working best is selecting a main folder, such as "vacations", selecting all the contents and then selecting "Command N", to create a new album of all the contents combined. I then opened that album selected all and hit delete. The biggest problem is the slow speed connection between the external drive and the iMac I found 30,000 photos that I wanted to delete and it's currently erasing those right now. It has been over 12 hours and still running.
I'm sure you're curious why I'm doing all this so I'll give you a brief description. I play in a band and I have all the band photos and archives. I want them on a separate drive in case something happened to me. Let's say on a tour or a trip and that drive could be given to historian or surviving member of the band without my 60,000 other photos of my vacations, other hobbies and private information shared.
I waited for many years for Apple to come out with a new high power iMac, but they never did so I finally bought a M4 Mac studio and display. I had a problem with the migration with the studio saying it migrated successfully with iMac saying it didn't so that's why I'm trying to save a lot of this information off my old computer to make sure I have it as an archive. The new Mac studio even though I bought a fancy version with an upgraded memory and a terabyte hard drive is in the process of a four day time machine back up, (which apple care says is normal???) but that's another whole story.
Thanks again for everyone's help. I feel like I'm a pretty proficient Apple user but it seems like I'm always asking for help, when I get in trouble and don't have much that I can give in return other than sincere thanks!!!
Rob