You shall utterly destroy all the places where the nations that you are dispossessing served their gods: on the high mountains and on the hills and under every leafy tree.
English: “You shall utterly destroy” — From here [we learn] that one must uproot idolatry after it (i.e., pursue it to its complete eradication).
On the daf / in context: The doubled verb form teaches the obligation to be diligent and thorough in destroying idolatry, grinding it and scattering it or casting it into the sea.
Type of Learning
Derash on the doubled verb (Sifrei / Bavli) — intensity and thoroughness of the destruction.
What Is Learned
One is obligated to pursue idolatry to its complete eradication, not merely to remove it once.