2. Then hold down the Ctrl key of the keyboard and click on the layer panel (the place in the red box) to select this backpack pattern.

3. Next, click Select-Modify-Shrink in the menu bar above.

4. Click OK.

5. Then deselect and delete.

6. The execution result is shown in the figure below. If the effect is not good and there are still miscellaneous edges, you can repeat the above steps.

Here are some extended knowledge:

In the lower version, we can use the "anti-aliasing" command, set the feathering radius, and directly create a selection with gradually hidden edges. But once the selection area is established, it cannot be changed directly.

If you want to make more detailed changes, you must resort to complex operations such as channel, mask or quick mask. In Photoshop CS3 and above, there is a very lovely selection assistant tool "Adjust Edge". Using a series of sliders and display modes on it can solve the problem of mixed white edges.