How do I close my business /get a letter from the irs that my self-employed llc is dissolved /closed?

Who sent the notice ?   Usually it is the state if you fail to file an annual return or fee.   And what form does the LLC file ?   A Sch C on the personal return ?   Or an 1120S  or  1065 ?

Nobody sent a notice. I'm asking how to go about doing it and getting a letter from irs as proof.