All you need to say is

That sounds great. But I am sorry we do not need this plan at this moment. Thank you and good luck! Stay safe.

這些都是標準拒絕的回答。他們如果再說你就啥都不說。微笑著說，i am sorry. 再不停，微笑就收起來，good luck， 把門關上。

還有完全可以和他們說：if you do not mind, I would really appreciate you put on your mask .