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: 
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".
If you really, really want to get rid of the file, you can always boot to something like a Linux or Windows PE boot disk, and then delete it.

If it was placed there by the current OS, it will come right back. However, from your wording, it sounds like it was placed on the old HD by an old OS that was on it.