Chosen Solution

I read that for new 27" iMac removing back stand is not possible. I want to put this iMac on wall mount accessories of VESA. Please tell me how to do it?

Sadly, Apple does not offer a way to upgrade the newer ‘Thin Series’ iMacs to a VESA mount. Sorry ;-{ But! They do offer a way to purchase a unit with it: Buy iMac with Built-in VESA Mount Adapter. So you could see if you can sell your system to buy a new one. Thats the best you can do here. Keep in mind the amount of work to get the stand off is quite large and there is a risk you could damage something in the process. You would still need to find someone who could make you a replacement part. Added up, getting a new system would be cheaper.