Photos can be deceiving. From what I see, if it were my mirror, I would clean it.
This is the method I have been using for the past several years.
Removing the mirror is straight forward. I lay the scope horizontally is a secure place. A carpet on the floor.
It's handy to mark the cell and tube so it's easy to tell the proper orientation when you reinstall the cell. The tube has a seam and the cell has a notch that lines up with the seam so marking it is not really necessary but it makes things easier.
The should be a series of screws around the tube at the bottom next to the cell/ring.
Remove those being careful to keep the cell in place. When the screws are out, remove the cell and place mirror side up securely on a table.
You will see the mirror clips that restrain the mirror. Remove the screws and remove the clips. The mirror should be free.
When you are ready to clean the mirror, remove it, and follow the instructions on the video. Use a very light pressure with your fingertips, a very gentle massage. After the mirror is dry. Install the mirror in the cell, install the clips but make sure not to tighten then too much. The should almost but not quite touch the mirror.
If the clips are tightened, they pinch the mirror causing astigmatism, it doesn't take much.
Install the cell in the scope, collimate and your ready to go.