Yes and it is very simple. Check out the prepublish source code to see how. There are 2 functions, startPublishing() and stopPublishing() which achieve this.
Primarily they use session.publish(publisher);
to publish and session.unpublish(publisher);
to unpublish.
Here is code I have used to work off:
// Called by a button to start publishing to the session
function startPublishing() {
if (!publisher) {
var parentDiv = document.getElementById("myCamera");
var publisherDiv = document.createElement('div'); // Create a div for the publisher to replace
publisherDiv.setAttribute('id', 'opentok_publisher');
parentDiv.appendChild(publisherDiv);
var publisherProps = {
width : VIDEO_WIDTH,
height : VIDEO_HEIGHT
};
publisher = TB.initPublisher(apiKey, publisherDiv.id, publisherProps); // Pass the replacement div id and properties
session.publish(publisher);
show('unpublishLink');
hide('publishLink');
}
}
//Called by a button to stop publishing to the session
function stopPublishing() {
if (publisher) {
session.unpublish(publisher);
}
publisher = null;
show('publishLink');
hide('unpublishLink');
}