How to delete Yosemite partition?

so, installed yosemite developer preview on separate partition on macbook pro retina display 13", late 2013 $1499 model. (remained unchanged in last update)

thinking clever, thought use casually wipe , install real thing on mavericks when came out. herein lies problem: no longer appear able control either of partitions part of os. greyed on in disk utility whether in yosemite, mavericks, or recovery. i'm not terminal yet, have feeling solution going involve @ point.

on side note, incompletely wiped windows partition while back, windows partition still visible when hold down alt @ startup. ideas why? it's invisible in disk utility , startup disk can still see if hold alt @ startup.

thank graciously can provide. thank you.

 

you've got sort of core storage logical volume there. revert partitions normal , can edit partitions in usual way.

if yosemite installer creates logical volume groups, can run in terminal partitions normal. make recovery partition visible when boot when holding option key down.

diskutil cs list

, then

diskutil corestorage revert lvuuid

lvuuid last lvuuid reported previous terminal command.

restart normal after have run these commands in terminal.

 

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