Learn more about intermediate data
It is up to you whether you want to delete the intermediate data. The case for deleting intermediate data is that it tends to clutter up your workspaces with unneeded data. However, you may have created map documents with layers based on intermediate data, and if you delete the intermediate data and open the map document, these layers will be empty. The case for preserving intermediate data is that you want to preserve the process states between model edits.
When you delete intermediate data, the model will return to the ready-to-run state.
NOTE: Validating a model does not delete intermediate data.