From the Contacts tile.
Select and tap on an existing contact from your contact list. Tap on the messaging bubble under the contact profile.
From the Message tile.
1. Tap Messages from the menu on the left.
2. Tap in the top right corner to start a conversation. Tap [ + ] to choose recipients from your contact list or simply type in a number.
From the History tile.
1. Select a contact or a number you want to message and swipe or tap and hold for couple seconds to reveal the Message bubble.
Remove conversation/message history.
From your Messages tile – swipe or tap and hold for couple seconds the conversation you wish to remove and tap [Trash].