I assume you are asking "I am 15, I have been charged with truancy and I will turn 16 before the matter is heard in Court, will the charges be dropped when I turn 16?" It is very unlikely the charges will be dropped under those circumstances. I assume that you are planning to drop out of school at 16 (Not adviseable), but the alleged act of truancy had still occured.
Dropping out may make the District Attorney decide not to presume charges as the point of truancy is to get kids back in school, but there is no gaurantee they use their discretion to do so.
