We pull data from Facebook when creating a profile, so in order to change your name, you will have to change it on your Facebook account.

Once you have changed your name, follow these steps:
1. Uninstall the app (don't worry, it won't delete your account)
2. Restart your phone
3. Go to App Store or Play store
4. Install latest version of the app

For your reference, here are Facebook's rules on changing your name and how often you can change it.