You can drag a TapArea element from the Components panel onto the stage, resize to fit over your object and add this Event to it:
Target: gwd-taparea_1
Event: Tap Area > Touch/Click
Action: CSS > Set styles
Receiver: select your object to disappear
Configuration: +Add property > visibility:hidden
OK
That one event should do it, remove the other event that didn't work.
Hope that helps,
Kent
Google Web Designer team