NEC4 Option C, not to deduct delay Damage

The project was delayed but the Client agreed that the delay damage will not be applied. What is the paperwork has to be done by the PM? Option X7 is applied.

Any agreement to vary the contract, in order to have effect, has to be confirmed in writing and signed by the Parties (i.e. Client & Contractor) - I would suggest a Deed of Variation setting out exactly what the agreement is, assuming there’s a bit more than just waiving the LDs.

is there any clause I can refer to? such as how can I make it to be real under the NEC4 contract

It’s all based on clause 12.3 - check for any amendments.