Hi @SynthED, when you say “select a layer” do you mean that you just click it or copy it with Ctrl+C? As @KashouC said you can use the Escape key to deselect the layer, anyway I would like to know why you needed to do this.
For example, I saw that the Escape key trick sometimes is needed if we don’t want to move all the cels of the layer and we click it by mistake (something that can be avoided unchecking the Edit > Preferences > Selection > Transform cels in selected layers or frames on timeline option too).
I was just curious to know if something is not working as expected.