I will have to look at that.
Before you couldn't manage content unless you had a game installed.
For me, content wouldn't even show up for management.
It may be for bundles only, when I search kalimba and click "Ultimate kalimbundle" tile, I have an option to manage it, but if I click "Co-optimistic level pack" or "Dark void level pack", it just says installed and I can't delete them. That could be down to just buying the bundle rather than them separately though, maybe if I bought the dlc's seperately it would allow me to manage it?
If you buy/download the link I posted.. it's definitely possible to delete it. You have my word on that. I just deleted mine two seconds ago and it worked with no problems. When I go back to the bundle page, it still says manage but when I click it, it allows me to install it this time rather than uninstall.
The only issue I can see arising is if they remove the bundle off the store, if they do that then I don't think there is any way to delete it, but I can't see that happening and if you're worried, you can purchase it now and redownload later.