Mount/Unmount EFI boot partition by Command Prompt on Windows

 Step 1: Open Terminal (Command Prompt) as Admin by press Windows + X.

Step 2: Input command

mountvol /?

The output will have some hint at the end and in my case it was upper image.

Step 3: You can try with volumes with note *** NO MOUNT POINTS *** (you need test one by one) to find out exactly EFI volume. The command to mount volume as below:

mountvol z: \\?\Volume{07434f9f-e9d4-11e9-84c3-7085c2c582c4}\

Step 4: For access this drive, you can: open Task Manager > File > Run New Task, and browse to it.

Step 5: For unmount this drive, you can open Terminal (Admin) and run below command:

mountvol z: /d /n

 Final.