I have an extract published in server. The source of this extract is webconnector written in an html page and under "Connects to" it displays the url to the html file. Even though I am the admin of Tableau server, I don't have access to the location of this html file. Is it because of this reason that I am unable to edit connection of this extract? I see edit connection greyed out for this extract.
are you talking about published datasources and are you trying to edit the connection for workbook such as the attached screenprint?
If so, go directly to the datasource, by clicking on the link within "connects to" and then you should be able to edit the connection there. The only thing I'm unsure on is if you can edit it for WDC.