When I first installed Windows 7 OS on my computer for the first time, I kind of screwed up. I tried to separate my 1TB hard drive into 3 different drives, 450GB, 50GB and 500GB and somehow the 500GB drive did not get registered and I'm stuck using a 450GB and 50GB drive for about a year (but that didn't really affect me because I never really needed 1TB).
So then there came a time when I decided I needed to reinstall Windows 7 and while choosing where to install Windows 7 on, I remembered that I still had the 500GB hard drive left untouched so I decided to install Windows 7 on the 500GB drive. Then after rebooting my computer I suddenly had 2 OS's and although this doesn't really affect me or my PC performance in any way, it is kind of that extra thing on the side that drives me nuts everytime I boot my computer.
Anyone can give me a set of instructions on how I should reformat my drive so that it becomes 1TB again so I can allocate the space differently again and try not to screw up this time. Also have only 1 OS at a time?
For safety, always keep a backup of all important files before you attempt to modify your hard disk in anyway.
Boot into the Windows PE environment and use DiskPart to delete existing partitions. create a new partition and set it to active. Format this and you are ready to go. After OS installation, you may use disk management to Shrink your volume and create additional partitions.