delete hibernation files

If you want to delete that file because you're that low on disk space you already have lots of problems.

We're in "really bad idea" territory here 😟

You have to delete it.

http://www.macworld.com/article/53471/2006/10/sleepmode.html

Recover some drive space

If your machine was previously set to mode 3 (or 7 ) and you’ve reverted to the old style sleep mode, you’ve got one more step to take: recover the drive space used up by the copy of your system’s RAM, which was created the last time you slept the machine prior to making the switch. In Terminal, enter these two commands, pressing Return after each and providing your password when asked:

cd /var/vm

sudo rm sleepimage

If you ever return to the new style sleep mode, the sleepimage file will be automatically recreated when you execute the sudo pmset command—yes, it creates the file as soon as you execute the command, not the first time you put the machine to sleep.