How to turn closed paths into opened paths. ex O → C

[RickyI]

Hi.

How can I turn closed paths into opened paths?
For example, I have a path, the shape of "O". How can I turn it into "C" shape?

Deleting just the node didn't work because the path still maintained closed.

Thank you for reading.

[Moini]

Split the path between two nodes, see: http://write.flossmanuals.net/start-with-inkscape/_draft/the-node-tool/ ("Break path")

[RickyI]

In the first try, it didn't look they were separate because it was filled with "flat red color", wasn't showing path outline and looked everything was connected. But after selecting "no paint", I could see that they were separate.

Thank you very much for helping me.