The chumash tells us that the magicians of Egypt were ale to replicate the plague of frogs:
וַיַּעֲשׂוּ־כֵן הַחַרְטֻמִּים בְּלָטֵיהֶם וַיַּעֲלוּ אֶת־הַצְפַרְדְּעִים עַל־אֶרֶץ מִצְרָיִם׃
"The sorcerers did likewise with their magic art, and made the frogs emerge upon the land of Egypt."
The next pasuk tells us that Pharaoh had requested Moshe to ask God to remove the frogs
וַיִּקְרָא פַרְעֹה לְמֹשֶׁה וּלְאַהֲרֹן וַיֹּאמֶר הַעְתִּירוּ אֶל־יְהֹוָה וְיָסֵר הַצְפַרְדְּעִים מִמֶּנִּי וּמֵעַמִּי וַאֲשַׁלְּחָה אֶת־הָעָם וְיִזְבְּחוּ לַיהֹוָה׃
"Pharaoh called for Moshe and Aharon and said, “Pray to Adonoy, and let Him remove the frogs from me and from my people, and I will send the people to sacrifice to Adonoy.”
THE QUESTION: If the magicians of Egypt were able to replicate the plague of frogs, why was it necessary for Pharaoh to need God to remove them? Couldn't the magicians removed it the same way they (seemingly) made their replication go away.