If a person or contact in your phone book is irritating on WhatsApp messenger just block him. There is an option to block the person so that you won’t receive any annoying messages from him/her.
Block person on WhatsApp
Here are steps to reproduce and block contact or a person.
Step #1: go to chat window of the person you want to block and press right soft key for option.
Step #2: Click on More for more options on chat window. (Take a look at below screenshot)
Step #3: This will show you more option, then there is direct option to Block person directly.(Take a look at below screenshot)
Step #4: You have successfully blocked person now he/she won’t be able to send message.
Read: How to know that you have been blocked on WhatsApp.
Unblock person on WhatsApp
As you blocked the person you must have to know how to unblock in-case needed in future.
Follow same steps as above in #1 case of blocking, till Step #3. At Step #3, you will be getting option of Unblock instead of Block. Just tap on it with finger and person in chat window will be unblocked and you can receive his messages.
Read: How to send WhatsApp messages to blocked contact?