Storage of Photos library

You could move the Photos Library to an external volume to save storage on your Mac.

See: Move your Photos library to save space on your Mac - Apple Support

Or use iCloud Photos and enable the "Optimize Mac Storage" option to remove the high resolution originals from your Mac and keep them only in iCloud. Use iCloud Photos to store photos in iCloud – Apple Support (UK)

But you need a Photos Library somewhere, if you want to use Photos.

Do you mean that you have all your pictures stored in folders, and the pictures are also stored in the Photos Library? This would mean that in your Photos Preferences>General you have "Copy Item to the Photos Library" checked.

If that's true, then the original pictures that are in Finder folders are redundant and could be deleted. Of course, "redundant" is also called "backup." Personally, I would put those folders on an external drive, maybe a flash drive, before deleting them from the Mac, you know, just in case...

Are you syncing your Mac Photos Library with iCloud? That costs a bit (200GB is $3/month), but it's a simple and effective way to keep copies of your most important pictures off-site, and you get the benefit of having the same pictures on all your devices.

Are you talking about a referenced/managed library or using Photos as an editor without using the image organizing?

You certainly *can* use Photos as an editor, but there are much better programs out there for this.