To add to what klem says, 8 out of 10 wall mirrors that are applied to a wall with mastic will break in removal. More people get hurt trying not to break the mirror then they do just accepting and dealing with the fact it probably will break.

Thank you both for helping me with this. It's definitely glued. I removed the clips and tried to slide it, but it won't budge. I like the idea of the fishing line. Hopefully that will work for me. If not, out comes the hammer. lol ~ Thanks again.

pry bar, small flat shovel maybe?

Use packaging tape and cover the whole front of the mirror with it before you attempt anything else. Get some good grippy gloves, like Mechanix. Cover the vanity top with a cheap moving blanket. Wear safety glasses, and long sleeves.

Now you are set to try to remove it. Safely.

If it won’t budge, consider the moving blanket sacrifice. Tape it to the wall above the mirror, and only tap lightly through the blanket to break the mirror. Get the thicker cut resistant gloves to deal with this.

If you find it must be busted up in order to remove it,here's a little tune to work by. I broke the mirror