You can carefully remove the back and replace the picture, alternatively you can have fun upcycling them into new ideas. How about removing the glass and painting the hardboard with chalk board to make chalkboard? Stretching chicken wire across the back and using as a jewellery holder, hanging your earrings from the wire, arranging several frames as a modern lampshade. There are some great ideas here: https://www.sadieseasongoods.com/repurposed-picture-frames/
Thank you. Sounds perfect.