The reason I have came here to post a question is because it seems that looking for the answer doesn't work. After attempting (and failing) to install bootcamp, my disk has for some reason been divided into two different containers. I allocated half my storage to bootcamp, but it isn't usable so I need to delete it. I also don't have enough space on my hard drive and need to free up more space. The second container(2) is pretty much empty, it only has 125.8 MB used. I have tried partitioning it, but that doesn't work. For some reason, as you can see, the minus button is greyed out, but after I delete the 8GB of free space, the minus button no longer is greyed out. Of course, you would think that all I have to do is click the minus button and click apply... but that doesn't work. Instead, this lovely message shows up. The same message also shows up when I try to erase the container, but there isn't much to erase anyways. If it helps at all, I at first had 3 different containers, the third one being very similar to the second, only having 125.4 MB used. I then combined the second and third containers, hoping to get some sort of result, but it didn't change anything.
I hope this isn't a question that has already been answered, and sorry for all the pictures, but I thought they might help.