And his heart was lifted up— And when he had elevated his mind in following the commandments of God, he took yet from Judah high places and groves: i.e. he destroyed yet other monuments of idolatry, which had escaped the diligence of his father Asa, though he took not away those high places and altars which had been erected in Jerusalem for the true God. See 1 Kings 22:43 and ch. 1 Kings 20:33 of this book.
Related Commentaries of 2 Chronicles 17:6
2 Chronicles 17:6
6 And his heart was lifted up in the ways of the LORD: moreover he took away the high places and groves out of Judah.