Query on ITC Reversal on Restaurant Services

A registered taxpayer, providing restaurant services subject to a 5% GST with no input tax credit (ITC) allowed, claimed ITC of ₹100 in IGST, ₹7800 in CGST, and ₹7800 in SGST during the April-June quarter. They utilized available ITC to pay output tax liabilities: ₹7500 in CGST and ₹7500 in SGST from the IGST credit ledger. Please clarify :
1. The amount should be reversed in this quarter's return?
2. It should be reversed in all three ledgers or only in IGST ledger? and
3. The amount upon which the 24% interest should be calculated?