Depends on the range rules and your state law.
In my home state of Nevada, if you were over 14 (IIRC) and had a hunting license, you could use it without adult supervision. However, if you didn't have the hunting license, an adult had to be present.
It may be the same in your state. Or it may require all minors under 18 to be supervised. Or it may have a completely different law.
The range may also have its own rules on how old you have to be to shoot unsupervised. I don't recall there being an age limit at my range, but it does require that the person who has the actual membership has to be present.