Remove the ring left by photoframe

The oval is caused by fading due to light exposure. That can be reversed using a simple Levels adjustment. You have to restrict the Levels adjustment to the faded area using a mask. I drew an oval vector mask using the Ellipse tool in Path mode, but if you’re not familiar with vector masks, you can use the Elliptical Marquee tool instead. (I like vector masks because they are much easier to adjust later.)

When a selection or path exists, creating a new fill layer or adjustment layer automatically converts that to a mask. Then you only need to adjust the input and output levels until the area in the oval matches the rest of the image.

My demo below is very quick and rough, so you can see that the oval edges aren’t quite matched up perfectly. That’s just a matter of spending enough time to adjust the vector mask precisely.