With iOS 10 you can finally delete the stock Apple apps that you don't use. This will free up over 100MB of space if you delete them all, and there are a lot of apps you can remove.
All you need to do is long press on one of the apps and then tap the X. If you want it back, you need to go to the App Store and re-download them.
If you delete one of these apps you will lose the ability to rely on services they provide like weather or alerts.
You cannot delete every Apple app, but there is now way more control than you have on iOS 9.