I have permission to fly my spark indoors in my church gymnasium.  Since it's a rather large room, and I have no way to recieve GPS signal and no threat of flyaway I'd like to fly with just the RC and not have to worry about setting up with the mobile app, etc, etc.  

Is there a way to do it?

how?

It will work without GPS in Atti mode. Ensure you have the prop guards in place to protect from damage if it clashes with the structure.

I fly my Spark in my living room in Sports mode. Once you get hold of the sticks it’s very easy. As you mentioned no flyaways.

I wouldn't fly inside in sport mode.  

I believe you can disable all of the safety features and fly in normal mode, but you'd need to run the app to do so.  Putting it in sport mode also disables all of the safety features, but it makes the controller input a lot more exaggerated as well.  

Be careful indoor in ATTI mode.
Also note that the max height is limited (look in the manual for the exact height, I believe it is 5 meters height.)

I would recommend you fly with props guard and avoid things which have bad effect on VPS. Thanks for your support.