This file is installed with OS X and should not be deleted. In some cases, it may be visible in the Finder. The file can be hidden again using the following steps.
- 

- Login as an Admin user. 

- Open Terminal (located in /Applications/Utilities). 

- Enter the following command, then press the return key:


sudo chflags hidden /mach_kernel

 
 - Enter an Admin password at the "Password:" prompt. 

- Quit Terminal. 

Tip: You can copy the terminal command to your clipboard, and paste it directly into the Terminal window.