How to ensure we release resources in colab when exiting a notebook?

This is not really a topic on the course as such, but wanted to know how we ensure releasing of resources on colab server (runtime, GPU etc.) when we close the notebooks? Is it by hitting “Disconnect and delete runtime” from top right corner menu? Same question for our programming assignments in

For assignments, could this just be Kernel->Shutdown?

For coursera jupyter environment, shutting down the kernel is sufficient.
For google colab, disconnecting and deleting runtime will clear all runtime resources allocated for the notebook.

Thanks for your help.