65 ILCS 20/21-29
Any candidate for alderperson under the provisions of this article may withdraw his name as a candidate by filing with the board of election commissioners of the city of Chicago not later than the date of certification of the ballot his written request signed by him and duly acknowledged before an officer qualified to take acknowledgements of deeds, whereupon his name shall not be printed as a candidate upon the official ballot.
If any candidate at an election of alderpersons who was not elected as provided for in this article but who shall have received sufficient votes to entitle him to a place on the official ballot at the ensuing supplementary election shall die or withdraw his candidacy before such supplementary election, the name of the candidate who shall receive the next highest number of votes shall be printed on the ballot in lieu of the name of the candidate who shall have died or withdrawn his candidacy.
65 ILCS 20/21-29