how would i make a banana into a flour?

Answer 1

1. Peel the banana.
2. Cut the pulp into small slices.
3. Grind it in a grinder along with little addition of water.
4. Spray dry the ground banana pulp in a spray dryer.

or
1. peel the banana
2. Cut the pulp into small pieces.
3. Dry them in a hot air oven or solar dryer.
4. Powder in a dry grinder.
5. Sieve it for the required grain size.

Answer 2

you probably can't because there is too much sugar in the fruit and that makes it attract moisture. Maybe if you freeze dried slices to make chips and then grind them into a powder and vacuum seal the powder it will keep but it won't act like flour when you cook

Answer 3

By drying it out.