It is a trivial typographical mistake.It is rectifiable. It is bona fide mistake.Produce original records before the officer who has issued notice/letter. I think it is not a Show Cause Notice but a simple letter. Mere wrong entry cannot force you to reverse ITC with interest as per GST laws. You have not caused any revenue loss. Hence no question of interest and penalty.
SECTION 126. General disciplines related to penalty. - (1) No officer under this Act shall impose any penalty for minor breaches of tax regulations or procedural requirements and in particular, any omission or mistake in documentation which is easily rectifiable and made without fraudulent intent or gross negligence.
Explanation. –– For the purpose of this sub-section, ––
(a) a breach shall be considered a ‘minor breach’ if the amount of tax involved is less than five thousand rupees;
(b) an omission or mistake in documentation shall be considered to be easily rectifiable if the same is an error apparent on the face of record.