Until they discovered the remains they claimed it never existed.
True they took the name from the Bible once it was discovered, yet those who now write about it and do history on it still claim the Bible is useless for historical purposes.
It is a valid statement, regardless if they originally took the name from the Bible. Now that they have other ancient archeological writings that use the same name for them from other cultures like ancient Assyrian and Babylonian records.
In universities where they teach about the ancient Hittites, they still refuse to admit the Bible is accurate for History.
Fact.
No, "they" didn't. And the Old Testament doesn't talk about a Hittite empire. What you are saying is simply not true, period.