crop single layer

In Photoshop, you can use frames for this. Put the image in a frame and you can drag in the frame corners to crop it, as shown in the demo below.

If there were no pictures on the canvas already, you could use the Frame tool to draw empty placeholder frames that you later drop images into. But if you already have pictures on the canvas, you can put any layer into a frame by using the command Layer > New > Frame from Layers. In the demo below I selected just the one photo I wanted to “crop,” but if I wanted to crop them all, I would have selected all of the picture layers before choosing the command Layer > New > Frame from Layers.

In other words, in Photoshop, a frame makes a layer work more like it would in page layout software, where just that one object can easily be trimmed. After I put the bottom left image into a frame, I drag the frame corners inward to “crop” the image.*

A note on terminology: In most photo software, including Photoshop, “crop” means to trim the total document canvas, not individual layers. So although you want to “crop” one image out of many in the way you would in page layout software, when it’s one layer in a single image document, things work a little differently. That’s where frames come in.

(In older versions of Photoshop, or in other image editors that don’t have frames, you can still “crop” a layer by creating a pixel or vector mask that hides the layer edges you don’t want to see. But that takes a lot more steps than making a frame, so it’s very convenient that Photoshop added frames.)

*Note that you can manually crop with a frame as long as you haven’t applied any auto-fitting options to the frame.