CloseCurrentMatchMake 

Namespace: SynicSugar.MatchMake
Class: MatchMakeManager

public async UniTask<Result> CloseCurrentMatchMake(bool destroyManager = true, CancellationToken token = default(CancellationToken))

Description 

Host destroys lobby to cancel matchmake. After Host calls this, all Guests When Guest call this, just leave lobby.
This can only be called in mathmaking. SynicSugar judges in matchmaking or not based on the cancel token that we passed Create/SearchXXX.
If can, return true.
If we pass true to 1st arg, this will destroy ConnectManager after being able to cancel matchmaking. When we have the two scene for using ConnectManager and not, pass true.
2nd arg is for this Task. (It's not for MatchMaking but we can also use the same token.)

using UnityEngine;
using System.Threading;
using Cysharp.Threading.Tasks;
using SynicSugar.MatchMake;

public class MatchMake : MonoBehaviour {
    public async void CancelMatchMaking(){
        CancellationTokenSource cts = new CancellationTokenSource();
        CancellationToken cancelToken = matchCancellToken.Token;

        Result result = await MatchMakeManager.Instance.CloseCurrentMatchMake(true, cancelToken);
        
        if(result == Result.Success){
            //Success
            return;
        }
        //Failuer
    }
}