Brainfacts.org (links down below) says that this is actually a myth that 2/3 of our population believes:

“That we use only 10 percent of our brains. Hardly! Our neuron-dense brains have evolved to use the least amount of energy while carrying the most information possible – a feat that requires the entire brain. TED debunks this neurological myth (and explains why we aren’t so good at multitasking).” – Brainfacts.org (link down below video).

Copied off of: https://www.brainfacts.org/thinking-sensing-and-behaving/thinking-and-awareness/2016/what-percentage-of-your-brain-do-you-use-051716