When you detach a server keep in mind that when you want to reattach it, you need to chose which Ssrver has the project you want to keep.
Which means that you can't make modification on 2 separate machines and keep both of the changes.
To detach a server from the topology you can click on the Enable live Sync button or right click on a server and Disable Smode-Net Live-link
To re-sync a detached server you can click again on the Enable live Sync button or right click on the server and Enable Smode-Net Live-link
this will bring a popup asking you to chose the server that is the reference