Answer 1.
Download a program called Unlocker from here: http://filehippo.com/download_unlocker/
When you click delete on the file it will give you a prompt asking you what you want to do. One of these options is to delete. Make sure you really are deleting the right files otherwise your computer will crash and you will not be able to reboot without reinstalling the OS.
Answer 2.
Go to my computer, right click, go to properties. click the advanced tab then Settings on the startup and recovery section.
Click edit. That is your boot.ini file. If your computer by default it booting into the correct location then remove the entry that does not match under the part in the line starting with "default"
An example would be the following:
default=multi(0)disk(0)partition(1)\windows
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Home Edition"
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Home Edition"
)/NOEXECUTE=OPTIN /FASTDETECT /USEPMTIMER /USEPMTIMER
In this case you can see that partition = 1 in the default, so you'd remove the line that has partition(2) in it. Once done save it and exit. Be very careful doing this however as if you delete the wrong line you will not be able to boot into windows again without fixing that boot.ini file.