This question already has an answer here:
I got Yosemite via the Apple Beta Program. I installed Yosemite on a separate partition which I had created for the purpose specifically. Now I want to reclaim my 50 GB by deleting the partition. I have already set my startup disk to my original Mavericks partition.
So, if I launch Disk utility in Mavericks and delete the Yosemite partition, will my Mac still boot?
PS: I am not looking to uninstall just yet, but I'm running low on space and might need to get some space back soon enough (before Yosemite gets stable and I get the upgrade).