Disk Utility Fails to erase/format an HDD(Yosemite) MediaKit reports not enough space on device for requested operation

You have an older version of Disk Utility since you are using a system older than El Capitan. See if the following helps better.

Drive Partition and Format Pre-El Capitan

1. Open Disk Utility in the Utilities' folder.
2. After Disk Utility loads select the drive (out-dented entry with the mfgr.'s ID and size) from the side list.
3. Click on the Partition tab in Disk Utility's main window toolbar.
4. Set the number of partitions to one (1) from the Partition Scheme drop-down menu.
5. Set the Format type to Mac OS Extended (Journaled.)
6. Click on the Apply button.
7. QuitDisk Utility after the process is completed.

Do you see the drop-down menu labeled, "Current"? Use it to set the number of partitions to one (1). It's essential you get rid of that topmost partition labeled, "disk0s1". It should not be there.

In order to reformat an internal disk, you must boot the computer from another device. I don't know which model of MBP you have, but if it is a Retina model then you should be able to do a Network Recovery:

Internet/Network Recovery of El Capitan or Later on a Clean Disk

If possible back up your files before proceeding.

1. Restart the computer. Immediately after the chime hold down the (Command-Option-Shift-R) keys until a globe appears.
2. The Utility Menu will appear in from 5-20 minutes. Be patient.
3. Select Disk Utility and click on the Continue button.
4. When Disk Utility loads select the drive (usually, the out-dented entry) from the side list.
5. Click on the Erase tab in Disk Utility's main window. A panel will drop down.
6. Set the partition scheme to GUID.
7. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
8. Click on the Apply button, then click on the Done button when it activates.
9. Quit Disk Utility and return to the Utility Menu.
10. Select Reinstall OS X and click on the Continue button.

Note: This should install the original version of macOS that was pre-installed from the factory. If all works well then you can upgrade to the latest version of macOS by downloading the Mojave installer from the App Store: Get MacOS Mojave now from the Mac App Store.

You will see two different entries. One is out-dented while the other is indented. The latter would be "Macintosh HD" on your system. The entry above it is the one you want to select for the procedure I posted.

Here is a pic of mine. The out-dented entry is "Fusion Drive" on my system. If Disk Utility does not show a similar layout then in the upper left side of the toolbar is a View option. Change it to show All devices.

Try after clicking in the bottom partition. If that doesn't help then it will require some Terminal work to fix the problem. That topmost partition is, in fact, the disk's EFI but it should be invisible. But try reformatting the Macintosh HD volume by clicking in the partition. This should enable you to install macOS.

You want to select this entry:

Macintosh HD <==== Select this one

Macintosh HD

No Name

You have it correct as I showed it. Select the topmost entry labeled, "Macintosh HD." It corresponds to the entry labeled, "Fusion Drive" on the image I posted.