How to take off the entire top of a PS4

I suppose the iFixit teardown guide will help you there. You can see the top removed on the second picture of step 11. In case you want to go further the remaining steps show you how to completely disassemble the console (and read the steps backwards to reassemble it).

They also states that, having no adhesive, the disassembly and reassembly is easy, so you shouldn't have any issue putting back the standard top or another one if you want to customize your console.