Another interpretation: "You shall have no other gods" - why is this said? Because it says "You shall not make for yourself a graven image or any likeness" (Exodus 20:4). I would know only that one may not make one; from where do I learn that one may not keep one already made? The verse teaches, saying "You shall have no other gods." But are they gods? Surely it has already been said "and they cast their gods into the fire, for they were no gods" (Isaiah 37:19). Then what does the verse teach by saying "other gods"? Rather, that others call them gods.
You May Not Even Keep an Idol Already Made
Yalkut Shimoni on Torah 286:12
דָּבָר אַחֵר לֹא יִהְיֶה לְךָ לָמָּה נֶאֱמַר, לְפִי שֶׁהוּא אוֹמֵר "לֹא תַעֲשֶׂה לְךָ פֶסֶל וְכָל תְּמוּנָה" אֵין לִי אֶלָּא שֶׁלֹּא יַעֲשֶׂה, הֶעָשׂוּי כְּבָר מִנַּיִן שֶׁלֹּא יְקַיֵּם, תַּלְמוּד לוֹמַר לֹא יִהְיֶה לְךָ אֱלֹהִים אֲחֵרִים, וְכִי אֱלָהוּת הֵן וַהֲלֹא כְּבָר נֶאֱמַר (ישעיה לז, יט) "וְנָתֹן אֶת אֱלֹהֵיהֶם בָּאֵשׁ כִּי לֹא אֱלֹהִים הֵמָּה", וּמַה תַּלְמוּד לוֹמַר אֱלֹהִים אֲחֵרִים, אֶלָּא שֶׁאֲחֵרִים קוֹרְאִים אוֹתָם אֱלֹהִים.