"Won't let me wipe my main hard drive" - I am presuming you mean the OLD main drive that had your OS on it and got corrupted.
You don't explain how you are trying to "wipe" it. But MAYBE the problem is that Windows really will not Format a HDD that already has Windows installed on it. This is a caution move to make sure you don't cause yourself a disaster. Although it would be quite OK to do this in your situation, Windows does not know that.
I can suggest two ways to try:
1. This one is easier. Use Windows Disk Management to find that old drive - make SURE it is that one, and not the other that you already have a NEW Windows installed on - and Right-click on the Partition it contains. Choose to Delete the Partition, and any others it may have. Windows may do this, or may continue trying to protect you from your own "mistake". If it works and you get all Unallocated Space, then you can Initialize it or Create a New Simple Volume.
2. If Windows won't co-operate, you need a disk utility that will do a Zero Fill on your old drive. This is often included in a set of disk testing utilities, and some of those are available for free download from the maker of your old drive. Be VERY SURE which drive you're doing this to - it will completely destroy all your old data on that drive! When it's done, your old unit will be wiped really clean and empty. Then you can use Disk Management to Initialize etc.