If a school receives a letter from the Department of Homeland Security that says a student is receiving their U.S. citizenship, do we remove the immigrant status on their enrollment page in infinite campus? And do we need to do anything else?

Immigrant status is a code used for federal Immigrant Grant funding under Title III and is unrelated to immigration status. Students are considered immigrants for funding purposes during their first three years in US Schools. There is no action to take as a result of immigration status changes like the one described.