Make sure to have iTunes installed so the right driver is installed and confirm on the device to allow PC access to iPhone.
Go to This PC, locate device name, and access the iPhone storage drive and inside should be a folder called DCIM where all the pictures will be stored and you may see tons of folder inside which are categorized.
I would copy all the contents in that folder to PC and then sort it after. If you choose to remove the pictures on the iPhone to your PC then "Cut" and paste.
An alternative, you can use Cloud backup like Dropbox, Google Photos and you can access all the pictures online and download it to any device for easy retrieval.