When prying up the speaker, take care not to damage the flex cable you just disconnected. If necessary, hold it to one side so the speaker has room to come out.

Insert a spudger under the top edge of the speaker near the edge of the iPhone's case.

Gently pry up and lift the top edge of the speaker.

When reinstalling the speaker, check the position of the flex cable and make sure it doesn't get trapped underneath the speaker.