Click the  Messaging icon at the top of your homepage.

Select the message from the list on the left pane.

Note: Once you select a message, the entire conversation thread of that message is shown on the right.

Click the  More icon on top of the conversation thread and select Mute conversation.

Once a conversation is muted, you'll see a Muted icon next to the contact's/conversation's name in the message list on the left pane.

Select the Muted conversation from the messaging list.

Note: Once you select a message, the entire conversation thread of that message is shown on the right.

Click the Unmute button near the upper right of the conversation.

Tap the  Messaging icon on the upper right.

Swipe left on the conversation you want to mute, select More ,and tap Mute.

Once a conversation is muted, you'll see a Muted icon next to the contact's/conversation's name in the message list.

Select the Muted conversation from the messaging list.

Swipe left on the conversation you want to unmute, select More ,and tap Unmute.