Since you don't want to add WeChat to someone you don't know, you can tell him that you seldom use WeChat. Please call. In fact, no matter how tactful you are, the other person will definitely not be too comfortable. You can be flexible in the future, WeChat can be added, and your circle of friends can block each other. If you want to chat with you, you can also choose to postpone replying to him for a few days, and gradually the other party will have no enthusiasm for chatting. Many friends have many roads, and unfamiliar people can get familiar with them through communication, which may be helpful to you in the future.