1999 Chevrolet Suburban fuel leaking

If that is a hex fitting, you should be able to screw it out. Use proper wrench or socket and be careful with the threads. If the fuel rail is aluminum and the valve doesn't come loose easily, I worry about the threads. If you screw up those threads, good luck getting it to seal.

If we're talking about the same thing, I call it a Schrader valve. Some parts books call it a fuel rail pressure relief valve.