Remove all partitions and reinstall MacOS I want to reinstall macOS but when I tried to repartition everything it only gave me 125 GB to install the OS on even though it's a 3TB drive. I think there may have been some kind of partition corruption because the computer was acting weird before all of this. 

Basically trying to get back to square one and remove all partitions so I can do a fresh install but not sure where to go from here and why there is so much in this list (see image below):



Any advice would be great.
You have shown no evidence the internal drive is 3 TB in size. Assuming you are correct, then proceed as follows. 


Boot to the USB Sierra installer.
From the menu bar select to open a Terminal Window.
Enter the command given below.

diskutil partitiondisk disk0 1 gpt jhfs+ "Macintosh HD" R

Quit the Terminal application.
Install Sierra.



  Note: The drives shown as disk images are just temporary drives created when you booted from the USB installer. This also occurs when you boot to a recovery volume or from internet recovery. The disk images are not stored on your internal drive.