Why does it say "ha'Gag Aliyas Achaz"?
Radak: The word [Gag] Samuch to Aliyas is omitted. It should say ha'Gag Gag Aliyas Achaz. Also "ha'Aron ha'Bris" (Yehoshua 3:14) is like ha'Aron Aron ha'Bris. Perhaps Achaz built the roof for this Avodah.
Why didn't Chizkiyah destroy Achaz' roof?
Malbim: It sufficed for Chizkiyah to nullify their Avodah. Also Menasheh, after he repented, nullified the Mizbechos he built in Chatzros Beis Hashem (but did not destroy them). The same applies to the Mizbechos that Shlomo's wives made, like the Meforshim say that afterwards, they offered on them to Hashem, especially according to the opinion that 'he wanted to build, but did not build.' You cannot say that he did not build at all, for they existed (verse 13)! Even though they offered on them to Hashem, Yoshiyah destroyed them, for there was an element of abomination in them.
What is the meaning of "va'Yaratz mi'Sham"?
Rashi, Targum Yonasan: He eradicated them from there.
Radak: He demolished them. This is like "Becha Arutz Gedud" (Tehilim 18:30). Perhaps the root is Ratzatz.
Radak citing an alternate text of Targum Yonasan: He distanced them from there.
