How do I get a platform to vanish?

I'm making a platformer and I have a switch which toggles between two worlds (yes, it's for Ludum Dare!), each of which has platforms in different positions. Currently, I have it set so that when the switch is toggled, the platforms from the old world turn invisible and their solid behaviour is disabled. This works fine to an extent - if you now try to jump on one, you can't - but if you are already standing on one then you don't fall down as I'd like. The platform vanishes but continues to hold you up. What can I do to fix this? I don't want to have separate layouts for the two worlds because that seems to cause a lot of problems with keeping many sprites global.

Thanks in advance!

Its the player platform behavior not triggering any events to make it move. Maybe something like set-y to "player.y - 1" to give it a kick

Thanks! That does the trick nicely.