without adult supervision:

"Persons under 15 years of age may not operate a motor-assisted scooter using the motor unless the person is under the direct supervision of the person’s parent or guardian."

https://dld.utah.gov/mc-motor-assisted-scooter/#:~:text=Persons%20under%2015%20years%20of,the%20person's%20parent%20or%20guardian.