Q: copying my photos that have been already copied to my iphone

You will need to either email the photos to yourself and open the emails on the computer and download them from the email or the other option that my be preferable if the quantity of photos makes that impractical would be to use a 3rd party app such as https://www.wideanglesoftware.com/touchcopy/

If you are a windows user - try this

Get OneDrive from Microsoft - they give you about 5 GB free space upfront or you can get 15GB from Google Drive

Download the app to the iPhone (they are free as well)

Upload the pictures to your account

Then delete them from the phone

If you want - you can log into the OneDrive or Google Drive from the PC and download your pictures

I forgot to say that after you have recovered the photos, if you then want to delete them from your phone you will need to connect the phone to your computer and then use iTunes to sync as instructed in the information below from Sync photos from your computer to your iOS device using iTunes - Apple Support

1. In iTunes, locate and click on your device.
2. Click Photos.
3. Choose "Selected albums" and deselect the albums or collections you want to delete.
   To delete all synced photos, deselect "Sync Photos from" and, when asked, click "Remove photos."
4. Click Apply.

Learn how to delete photos and video synced from iTunes when you can't access the originals.