Question: Ok, so I know what hiberfil.sys is, and I want to use hibernation on my laptop.

But I have another hard drive active in my laptop, it's taken from my old one... and I want to get rid of the hiberfil.sys on that drive. But even with admin privileges I can't delete it.

Any ideas?

Answer: 
I wanted to do this in the easiest way possible, especially without rebooting.

Open a command prompt as administrator and go to the disk where hiberfil.sys resides. In my case:

```
C:\Windows\System32\> e:

```

In e:, check for hidden files:

```
E:\> dir /A:H

```

In the listing hiberfil.sys should show up. If so, delete it:

```
E:\> del /AS hiberfil.sys

```

I have to warn you: I don't know what happens if you do this with an active hiberfil.sys file. In my case it was on an old hard disk drive and was no longer needed.
To delete restore file you can open command prompt with admin privileges and run command

```
powercfg -h off

```

Then reboot, and Windows should automatically delete your `hiberfil.sys`. If it doesn't, you can remove it manually.

Then running

```
powercfg -h on

```

restores sleep and hibernate functionality.

You can start command prompt with admin privileges by starting command prompt (`Windows Key`+`R` (Run), type `cmd`) and then right-clicking command prompt icon on task bar and selecting "Run as administrator".