two boot system - how to delete old one !

re partition drive or format

 

For an actually helpful reply ... read the following (from a TechNet post):

From the response created by a Microsoft engineer:
1. Click Start.
2. Type the three letters cmd into the Search box.
3. Press Ctrl+Shift+Enter
4. Click on Run as Administrator.
5. Type the following commands:

Type bcdedit /enum in the command prompt, this gives you the list of entries present for the Operating System.

A boot entry consists of 4 main elements:
1. Identifier: The identifier is how the system has named the boot entry.
2. Device: The device is the drive or virtual image that the system will use to boot the boot entry.
3. Path: The path is the location on the device where the bootloader file is found.
4. Description: The description is the friendly name we give to our boot entry, e.g. "Windows Vista"

To change the name of the entry, you have to make a note of the Identifier for which you need to change.
Type bcdedit /set {type the identifier name} description “enter new name”.

To change the order of the Entry, follow the commands below:
Type bcdedit /displayorder {type the identifier name} /addfirst

Refer the link for more bcd commands:
BCDEdit Command-Line Options: http://technet.microsoft.com/en-us/library/cc709667(WS.10).aspx