Say I have the black card how old do I have to be to come in without a legal gardian

You'll need to ask each location their policy based on state laws, but to my knowledge 18 years of age unless a permissions form is signed starting otherwise.

Best thing to do is check with the fitness manager at your location to see what is the age requirements are...

Yes it depends on location. Though my recommendation is to ask a location manager as it seems to me the younger employees tend to be less reliable with abiding that isn't the machines

Sara that works the front desk said 16

Some locations 16, others 18.