Can't modify partitions

[Usering]

For some reason, I can't modify my disk partitions. I look at Disk Utility in partitions and everything is greyed about and disabled. Here's a picture:

I want to delete the Yosemite disk, but as stated above, it isn't letting me remove it.

MacBook Pro with Retina display, OS X Mavericks (10.9.4)

 

[phrehdd]

Just a guess, when you brought up that screen, were you booting up Yosemite?
Try perhaps -

1) boot up into Mavericks and see if you can remove Yosemite.
or
2) back up your Mavericks partition and then boot up on the back (external drive) and just wipe the entire original drive and then copy over your external back up of Mavericks. While this is rather a brute way to do things, it should work.

 

[Weaselboy]

For some reason, I can't modify my disk partitions. I look at Disk Utility in partitions and everything is greyed about and disabled. Here's a picture:

I want to delete the Yosemite disk, but as stated above, it isn't letting me remove it.

MacBook Pro with Retina display, OS X Mavericks (10.9.4)

That is because Yosemite converted the partition into a core storage volume. Just follow this to delete it. Then you will be able to expand Mavs partition back into the free space.

 

[Usering]

That is because Yosemite converted the partition into a core storage volume. Just follow this to delete it. Then you will be able to expand Mavs partition back into the free space.

Turns out I had to erase the Yosemite partition and then it was unlocked to remove the partition.

 

[Weaselboy]

Turns out I had to erase the Yosemite partition and then it was unlocked to remove the partition.

If you follow those terminal steps it would have nuked the Yosemite partition and had the same effect. Some people don't seem to be able to erase it like you did and the Terminal method will overcome that. Glad you got it sorted.