There is no requirement to reverse the ITC already availed on capital goods purchased when the output supply (hotel room tariff) was taxable at 18% with ITC benefit. The restriction of “no ITC” applies prospectively from the date the reduced rate (5%) is opted/comes into effect.
As per GST provisions, ITC law does not mandate reversal of credit already validly availed merely because of a subsequent change in rate structure. Reversal is required only in cases of exempt supplies or where the capital goods are shifted to exclusively exempted/non-taxable use (Section 18(4) of the CGST Act, Rule 43). In your case, the supply remains taxable (at 5%), hence no reversal of earlier availed ITC is warranted, even if the capital goods are within 5 years of use.
Thus, you may continue to retain the ITC already availed before the rate change