1. Open the official seal image: In Photoshop, click the "File" option in the menu bar, select "Open" in the drop-down menu, then browse the folder on your computer to find the official seal image, and click the "Open" button.

2. Check the layer: After opening the official seal image, you need to ensure that the background of the image is transparent. In the Layers panel, click the lock icon in the lower right corner to unlock the image and make it editable.

3. Select the quick selection tool: click the quick selection tool in the main toolbar, or press the "W" key on the keyboard to select the tool.

Use the selected tools to make a careful selection in the official seal area. You can select an area by dragging tools, or you can use auxiliary tools such as "Add to Selection" or "Reduce Selection" to make an accurate selection.

4. Select the official seal area: use the "Quick Select" tool to draw a selection box in the official seal area. It is not necessary to completely cover the official seal, just roughly cover the main part of the official seal. If the selection is not perfect, you can add it to the selection by holding down the SHIFT key and clicking on other areas, or hold down the ALT key and clicking on the selection to reduce the selection.

After the official seal area, you can use the "Delete" or "Background Eraser" tools to cut out the selected area. Be sure to back up the original layer or use nondestructive methods such as layer mask for processing before operation.

5. Create a layer mask: In the Layers panel, click the Add layer mask button. This will create a mask on the image and apply your selection to the mask. Now only the area within the official seal is displayed in the image, and other areas are hidden.

6. Save the image: After the matting is finished, you can click the File option in the menu bar, select Save As, and then select PNG or other formats that support transparent background to save the image. Now, you have successfully removed the official seal.