Deleting Photos from iPhone SE2020

Are you using iCloud Photos on the iPhone? T

See this manual page: Delete or hide photos and videos on iPhone - Apple Support

When you use iCloud photos, any photos you delete or hide are deleted or hidden on all your devices.

Delete or hide a photo or video

1. Go to the Photos app  on your iPhone.
2. While viewing a photo or video, do any of the following:

• Delete: Tap  to delete a photo from your iPhone and other devices where iCloud Photos is turned on and you’re signed in to the same Apple Account.
  • Deleted photos and videos are kept in Recently Deleted for 30 days. During that time, you can recover or permanently remove them from all devices.

vegas75 wrote: … how do I delete photos off of apple iphone SE2020 running IOS18.6.1

Are you running into pictures that have no trashcan? This can happen with pictures that are transferred from a computer. Pictures that are transferred through a cable from a computer, perhaps with iTunes, can be shown by Photos, but they're not "owned" by Photos. So these pictures can't be edited or deleted by Photos, and they can't be synchronized by iCloud Photos The idea is that they are kept on the computer and transferred to the phone temporarily. One way to delete them is to use the computer to transfer an empty set of "pictures" to the phone, and the empty set will replace the others. In using iTunes for this, it may give the option to deselect the pictures that are already there. If you have a Mac, then you may be able to do it with the app Image Capture in your Applications folder. 

Another way to get rid of all the non-deletable pictures is to momentarily turn on iCloud Photos. You get a scary warning that these will be deleted. When you say OK, then they're trashed, and then Photos will start to transfer the other pictures to iCloud.But you can turn off iCloud and stop the sync before it happens.

If you want to save some of these non-deletable pictures, then you can use "Share" to save them to Files. Then re-import them from Files to create fully useable versions.