If you already have a visa stamp for another university and wish to attend IIT instead, you would need to cancel that visa and apply again using IIT I-20 or to transfer to IIT from within the US, if you are already at another university in the country.
If coming to IIT directly from another school, university or college in the U.S., the following F-1 transfer procedures must be completed:
First, you will need to submit a Transfer Release Form to the respective admissions office at IIT (undergraduate, graduate, Stuart, Kent or Institute of Design), completed by the international office at your previous school as well as copies of all previous I-20s or DS-2019s.
Then you will be issued an IIT SEVIS I-20/DS-2019 form. Upon your arrival in Chicago, you must report to the International Center within 15 days of the start date on your I-20 to complete the transfer of your F-1 status to IIT. Please remember to bring all previous I-20s to the International Center for check-in. Failure to do so will result in violation of your immigration status and will require the student to be reinstated by the U.S. Citizenship and Immigration Service. Students, who are transferring to IIT from another school in the U.S., may travel using their valid F-1/J-1 visa issued for the previous school and IIT I-20/DS-2019.