Hiding folders can further help a user navigate groups, especially with a large number of assets. Below are the steps to hide a folder.
By default it should open to "All Media". From here you can view all the files you have uploaded in your instance such as images, documents, and videos.
This will open your folder for you. In this case I wish to rename the "Brand" folder.
This will trigger a drop down with multiple folder options.
You will see it has now moved from the folders section in the sidebar to the hidden folders section at the bottom of the sidebar. You can view this section by expanding it.