If I signed in using facebook - how can I link my other social networks
Currently, when a user is already logged in with an account/social network, the SCLogin can show buttons to connect to other social networks (as you can see in our sourcecoast.com My Account menu). Additionally, if you have any of our login easy-tags on the page, you can use the 'show_reconnect' option to show these connect buttons as well.
or how to delink my fb account
In the current release, there is not a way to delink the connection to the social network.
In the next release, we'll have a layout where a user can manage their connected networks. It will allow them to easily make or break existing connections to each of the social networks you have enabled.
I hope this answers your questions, but let me know if you need more clarification.
-Melissa