Press the soldering tip to the connection point to detach the speaker from the motherboard. See this guide for information and tips on soldering and desoldering.

You will need to reattach these connection points when reassembling your device with the soldering iron. This guide will walk you through how to do that. Be sure to attach the positive and negative wires to the correct points when resoldering the connections.

You have now detached the internal speaker and the new speaker is ready to be attached.