Clock Color - Can you change digit color?

Well, there's always the eraser you can use. Oh, and shapeshifter, excellent explanation, I just have one thing to add: instead of promoting the selection to a new layer, you could also double-click on the Background layer and click OK in the dialog. The name is not important, but in doing so it automatically converts the background layer to a true layer. Now you can simply select the background like you explained and press Delete...