How to delete Yosemite partition?

[jolux]

So, I installed my Yosemite Developer Preview on a separate partition on my MacBook Pro with Retina Display 13", late 2013 $1499 model. (remained unchanged in last update)

Thinking I was clever, I thought I could use it casually then wipe it and install the real thing over my Mavericks when it came out. Herein lies the problem: I no longer appear to be able to control either of the partitions from any part of the OS. They are greyed over in Disk Utility whether I am in Yosemite, Mavericks, or Recovery. I'm not that good with Terminal yet, but I have a feeling the solution is going to involve it at this point.

On a side note, I incompletely wiped a Windows partition a while back, but the Windows partition is still visible when I hold down alt at startup. Any ideas as to why? It's invisible in Disk Utility and Startup Disk but I can still see it if I hold alt at startup.

I thank you graciously for any help you can provide. Thank you.

 

[tywebb13]

You've probably got some sort of core storage logical volume there. Just revert it to get the partitions back to normal and then you can edit your partitions in the usual way.

If the yosemite installer creates logical volume groups, you can run this in terminal to get your partitions back to normal. This will also make a recovery partition visible when you boot up when holding the option key down.

diskutil cs list

and then

diskutil coreStorage revert lvUUID

where lvUUID is the last lvUUID reported by the previous Terminal command.

Then restart for everything to get back to normal after you have run these commands in Terminal.

 

[jolux]

You've probably got some sort of core storage logical volume there. Just revert it to get the partitions back to normal and then you can edit your partitions in the usual way.

If the yosemite installer creates logical volume groups, you can run this in terminal to get your partitions back to normal. This will also make a recovery partition visible when you boot up when holding the option key down.

diskutil cs list

and then

diskutil coreStorage revert lvUUID

where lvUUID is the last lvUUID reported by the previous Terminal command.

Then restart for everything to get back to normal after you have run these commands in Terminal.

Will that fix the Windows issue too? Should I do this right before I install the first real Yosemite?

 

[jolux]

snip

How do I fix the Windows problem?

 

[nyc2pdx]

Also make sure file Vault is turned off for both partitions.

Sorry, not clue on the windows partition-good luck!