If you want several different still photos, duplicate the Live Photo several times. You can set the different keyframes for each copy, and then turn the photo into a still image. You cannot delete single frames within the Live Photo, but trim the eland of the video clip, see: Edit photos and videos on iPhone - Apple Support
To change the key photo or turn a Live Photo into a Still frame:
- Open the Live Photo.
- Tap Edit, then do any of the following:
- Set a key photo: Move the white slider on either end to change the frame. Tap Make Key Photo, then tap Done.
- Make a still photo: Tap the Live button at the top of the screen to turn off the Live functionality. The Live Photo becomes a still of its key photo.
- Mute a Live Photo: Tap 🔉, Tap again to unmute.
- Trim a Live Photo: Drag either end of the black frame viewer to choose the frames the Live Photo plays.