I uploaded photos from iphone 6s, how do I delete those photos from my iphone 6s

The Import panel in Photos has a checkmark "delete items after import" below the toolbar. if you enable this, before you import the items, they will automatically be removed.

But I would not use this option. It is safer first to check if the import succeeded, before you delete the photos from the iPhone.

Use the Photos.app on the iPhone to delete the photos.

I don't have the option to delete upon upload, afterwards or anything. My phone is maxed with pictures and I cannot possibly delete over 1000 pictures one at a time. Nothing has worked. Please help. iPhone 6S is what I have.

I don't have the option to delete upon upload, afterwards or anything.

If Photos does not show the "Delete items after import" option, you have probably iCloud Photo Library enabled on the iPhone. Then you simply can no longer delete the photos when importing. If that should be the case, either disable iCloud Photo Library, after you downloaded the photos, or enable "Optimize Storage" on the iPhone, or delete the photos directly on the iPhone. You can select all photos in a moment at once to delete them.

Ok, so now I have done all that you said. How do I select all the photos on my phone and delete them? I can't seem to do that, unless I have not turned off everything appropriately. Thank you.