Question for Jehovah Witness'. Should we discard the New Testament or the WTS as unreliable?

If the name Jehovah is so important, then why is it never used in the entire Greek New Testament? If men edited out the proper name of God, "YHWH", when they copied the New Testament, as only the WTS claims, thereby altering God's word, then how can we have confidence in ANY of the New Testament? Should we discard the New Testament or the WTS as unreliable?