Positive commandment · Mitzvat Aseh #156 of 613
To destroy chametz [before Pesach]
לבער חמץ
The verse · Shemot 12:15
שִׁבְעַת יָמִים מַצּוֹת תֹּאכֵלוּ אַךְ בַּיּוֹם הָרִאשׁוֹן תַּשְׁבִּיתוּ שְּׂאֹר מִבָּתֵּיכֶם כִּי כׇּל־אֹכֵל חָמֵץ וְנִכְרְתָה הַנֶּפֶשׁ הַהִוא מִיִּשְׂרָאֵל מִיּוֹם הָרִאשֹׁן עַד־יוֹם הַשְּׁבִעִי
“Seven days shall you eat unleavened bread; but on the first day you shall have put away leaven out of your houses: for whoever eats leavened bread from the first day until the seventh day, that soul shall be cut off from Yisra᾽el.”
The Rambam’s words
To destroy chametz [before Pesach], as [Exodus 12:15] states: "On the day before [the holiday], obliterate chametz from your homes."
לבער חמץ, שנאמר: "ביום הראשון, תשביתו שאור מבתיכם" (שמות יב,טו).
Why · Sefer HaChinuch #9
Disposing of chametz
“From the roots of this commandment are so that the Jews will remember forever the great miracles that G-d performed for them during the exodus from Egypt.”
Who & when
“And this commandment is practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Leavened and Unleavened Bread הלכות חמץ ומצה