Hi @Patricktseng,
Thank you for your question about removing a mirror from your bathroom.
I'll start by saying that you should take all necessary precautions when attempting to remove a mirror as it can shatter which might cause unnecessary lacerations. Make sure you wear gloves, eye protection, enclosed shoes, long pants and a long-sleeved work shirt. You should also have a second set of hands there as the mirror might is likely fairly heavy.
It's great to see you've already got some advice from @DIYGnome, who I agree with. If there is movement in any direction, it is probably mounted on a bracket or hook system.
The other way I can think that it may have been mounted is with silicone such as this Selleys Translucent Neutral Cure Silicone applied to the back of the mirror. If this is the case, you will need to lever the mirror off the wall using something like this Kango 380mm Flat Pry Bar.
Before you decide on a direction to take, could you take some images of behind the mirror by placing your camera as flush with the wall as possible and aiming behind the frame of the mirror?
This will likely shed some light on how it has been mounted and allow our members to give you more specific advice.
Let me know how you go.
Jacob
