Data marked as intermediate data in a model is automatically deleted when the model is executed using its dialog box or when the model is executed from the Python window. Intermediate data will not be automatically deleted when the model is executed from the ModelBuilder window in order to maintain a model's has-been-run process state. Intermediate data can be manually deleted within ModelBuilder to prevent the cluttering of the workspace with data that is not needed. When intermediate data is manually deleted within ModelBuilder, the model will return to the ready-to-run state.
To manually delete intermediate data after running a model in the ModelBuilder window, click Model menu > Delete Intermediate Data.