If your Facebook conversation history contains messages you do not want a third party to see, you can delete those messages -- or even the entire conversation -- by opening the Choose an Action menu in your Android Web browser or by long-touching a message or conversation in the Messenger app. Here are tips to delete your facebook chat history.
Messenger App
Launch the Messenger app and open the conversation that contains the message you want to delete.
Messenger App
Long-touch the message to open the Message pop-up menu. Select Delete to permanently erase the selected message.
Messenger App
Alternatively, to delete an entire conversation, long-touch a conversation in the main Messenger screen to open the Conversation menu and select Delete.
Web Browser
Launch your mobile browser and log in to Facebook. Select the Messages icon from the toolbar and open the conversation that contains the message you wish to delete. Tap the icon at the top of the conversation.
Web Browser
Select Delete Selected. Alternatively, if you want to delete the whole conversation, select Delete.
Web Browser
Tap the Delete icon next to the message you want to erase.