If you cannot murder because you are led of the Spirit, the Law does not apply to you. If you are not walking in the Spirit and can murder, the Law applies to you.Does not mean it was done away with.
Are you insisting the commandment not to murder has been done away with?
Let me state it this way.
The requirement for justification by keeping the Law has been done away with. Christ fulfilled the Law, and justification is now by grace through faith.
The Law is still perfect, and it has not been done away with, you are not saved through obedience to the law, but it does not take away from it's perfection.
Romans 2 through 3 explains it quite well.