I want to say it simply pries outward, but I haven't removed one of these in a while. If I am correct, and I think I am, you will want to get a bone tool or similar so you won't mar or indent the dash where you pry. Once you get one side of it up simply gently grab it and pull upward.
Thanks for all your tips!!! A few days ago when I tried to use a flat plastic stick to unclench the mesh, it didn't work and formed a small dent on the soft part of the dash. So this time I will try the way you suggested.
Thank yuckuJackD so much for such detail PDF file and again thanks a lot for otis44 and FCPGroton for your helpful suggestion!!!
I made a hook this time, removed the speaker grill and found the reason of the speaker noise. There was a small piece of paper (a label) on the top of the speaker which caused some noise when I played the music loud.