I'm going through my sd card and I found a folder called glu and it's 50MB. I have no idea what it is. I want to delete it, but wanted to make sure it's not an Android System File.
It's not, it's an SD cache folder for the Glu mobile app. If you don't use it any longer, then delete it and you'll be fine.
What is the glu mobile app?
EDIT: Nevermind I know where it came from. Super KO Boxing.