Ok. All I want to do i erase my entire HDD including ubuntu 12.04. I just bought win7, and I want to erase everything so I can boot that up. I have no important files, I just want it gone. I am having trouble doing that. I get access denied everytime i try to clear my HDD. Help please.
If you have one operating system installed, and you want to wipe the disk and install another operating system, you don't have to do anything in the first operating system for this.
Every OS that has an installer (including Ubuntu and Windows) is capable of erasing the old operating system when you install it. This would apply equally well if you were erasing Windows and installing Ubuntu.
It's only if you want to keep your first OS that you sometimes need to do something in the first OS before installing the second.
When you install the second operating system (whether it be Windows or any other OS), you will be able to tell the installer where you want it installed. You will have the option to format the disk or remove existing partitions.
Therefore, you do not need to do anything in Ubuntu.
You could boot from an Ubuntu live CD and erase the existing partitions, but there is no reason for you to do that, because the Windows installer (like any operating system's installer) is quite capable of doing that as part of the installation process.
On the other hand, if you want to recover some files, such as personal documents, from the Ubuntu system, you can use Ubuntu for that. (But since your Ubuntu system works, I'm guessing you've already done that. If the installed Ubuntu system were broken, you could boot from an Ubuntu live CD and access your files. If you need help doing that, please feel free to post a new question about that.)
If you need specific assistance using the Windows installer to wipe out the pre-existing operating system (in this case Ubuntu), that is beyond the scope of our site. For questions about how to use the Windows installer, you can ask somewhere where Windows questions are answered, like Super User.