i want to remove folders that were mistakenly copied to my phone from my laptop

If you put the photos onto your phone by syncing to your computer with iTunes, you will need to sync again using iTunes on your computer but change the settings/selection as described in the quote below from Sync photos from your computer to your iOS device using iTunes - Apple Support

Delete synced photos

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.

Files added from the PC can only be removed via the PC. Just find the picture folder you don't want sync'd and uncheck it on the PC. Re-sync and it'll remove them.

If you activated iCloud Photo Library, all your images will be available on all your devices. That's how it works. If you delete anything on one device, it will be deleted everywhere, so be careful.

If you are concerned about storage space on the device, select Settings > Photos & Camera > Optimize iPhone Storage. This will result inPhotos using only as much space as is free by reducing image resolution of the copies stored on your phone.