Is it possible to make UI appear and dissapear?

Like I have where you can unlock items and they have cooldowns but the cooldown number shows up when you dont have the item. Is it possible to make it not appear untill you get the item? Also I have enemies randomly attack you and theres a health bar but the health bar always shows up, Can I make it show up and disappear. I know this is probably a dumb question, I know how to make items show up and not through animations but numbers and health bars are different because there UI. Heres my game http://flowlab.io/game/play/933523

You can only hide labels with the alpha input, but bars don’t have that.

If you really want to hide the bars you can make an object that acts like an UI bar. Here’s an example:
http://flowlab.io/game/play/487532
You would have to make an animation in your bar object with frames for each value the bar can have. So if the bar’s range is 0 to 10, the animation will have 11 frames. With the goto input in the animation behavior you can take a specific frame from an animation and set the sprite to that frame.

I know it’s a lot of work but it has a nice advantage, you can make a custom bar that looks better than a normal UI bar.