Here are some ideas on how to cover the mirrors: https://www.hunker.com/13412323/decorative-ideas-to-hide-a-wall-mirror
You could add window film that comes in many prints, colors and designs. I used it to cover the large transome windows in my bedroom with green leaf patterns to look like outside but filter the light. You just apply with water and a squeegee. Amazon has an amazing collection.
Option 2 is to paint them.
Option 3 would be to just remove them, and repair the drywall. https://www.youtube.com/watch?v=Y_ckqmdqGYY I would tape the heck out it first to make safety my first priority, and wear a goggles and a heavy long-sleeved shirt.
You can sheet rock over them
Fabric and liquid starch. Install like wallpaper.
Hi ! A perfect solution for you would to use removable wallpaper ! Check out sites like wallsneedlove.com and tempaper.com