Question

it would be not possible for us to walk without friction why

Answer 1

Friction always opposes the state of motion, so if you try to walk, there must be a force to push you back otherwise you will just slip trying to walk.

Answer 2

You simply cannot. Friction is essentially a reaction force. Without friction, you cannot walk, but if you are successful to exert a lateral (or similar) force on something, you can expect the reaction force, and hence still be able to "move" away.