After careful inspection of the out of the box nodes available in Dynamo, many users wonder why there isn’t a delete node included. Perhaps, it was too risky for Autodesk to take any liability for the accidental deletion of hundreds of elements. Luckily, there are a few custom nodes available which accomplish the deletion task. After all, Dynamo through its Python scripting has access to the entire Revit API.
My preference is to use the delete node included in the SpringNodes package available from Dynamo’s Package Manager (I like Bakery best, which installs this package along with a handful of others). The node is very simple, you feed it Elements, the node deletes them and outputs a text list of element IDs deleted. One thing to note is that you may want to set your session to Manual instead of Automatic before opening/running the file. Here is a sample script you can try on the basic architectural sample project file in Revit (not your production file please).
A possibly useful application of this script could be creating a definition to delete unplaced rooms/areas. Having it available in the Dynamo Player, included in Revit 2017.1 and later makes it even easier to use.