In Lync, how would I convert one occurrence of an in-person meeting in a series to be an online meeting?

Open the meeting series in Outlook, click the "Online Meeting" button in the ribbon, then click Send Update.

You can refer to the following article for more details:

http://office.microsoft.com/en-us/communicator-help/work-smart-schedule-and-join-an-online-meeting-HA101871367.aspx

This is not telling me how to convert just one meeting of a series into and online meeting.  It appears that you are telling me how to convert the Series into an online meeting. 

I'd like to know how to do the opposite - once a meeting is an online meeting, how do I stop it being an online meeting - even if I delete the call details from the body, it still shows as an online meeting in Outlook.