I bought a iphone 4 off someone, how to reset?

I bought a iphone 4 off my grandma for 75$, it's in perfect condition besides a small crack, she still has all her stuff on it, basically I just wanna reset it so it's like I just bought it myself and can add my own stuff without going through hers.

Go to settings, general, then their is a reset option at the bottom. Choose that then select erase all settings and content

To restore your iphone, your going to need a charger. Take off the end piece, and then connect it to your computer. Then you have to download iTunes. Don't worry, it's completely free. I kind of forgot, but I think you then have to go to settings and click "restore" it should take about 20-60 minutes. It will clear all of the information, and it will be like brand new like you just bought it. Hope that this helped!