Can't ever remove partition?
Looks like your MacSSD2 partition has been turned into a Core Storage volume. Core Storage is Apple's underlying system for disk encryption - I assume you enabled encryption when you created the partition?

You can show the Core Storage volume group using the command diskutil cs list and then delete it using diskutil cs delete &lt;volumegroup-uuid&gt;, where you get the volume group's UUID from the output of the previous command.

That should either delete it entirely or make it deletable in Disk Utility.