You can hide single data layers, as well as entire groups at once.
To hide a single data layer, click on the eye icon next to the title of the layer. This will toggle off the visibility for this layer on your map, but will not affect other layers. To turn the layer back on, simply click on the eye icon again.
To hide a group of data layers, perform the same action as above, this time clicking on the eye icon next to the group name. This will toggle off the visibility for all of the layers within that group.