Hello Nick_112,
last day i have faced the same issue with my Lenovo i5, i want to remove factory installed window 10. I would like to share what i have faced with me. when i have try to installed a new window but it say to me that i can't installed on this drive because it is a GPT format style of your hard drive.
Unluckily at this point i have deleted my C: drive (windows drive).
After googling a lot i found i will be lost all data by converting my hard drive format GPT to MRT ro any other.
Note: Be careful while converting GPT to MRT or any other format.
At this point i totaly disagree with @RealBeast.
You buy a new window from anywhere even Microsoft but can't installed in your pc if you have a factory installed windows.
First, You should convert you hard drive from GPT to MRT to any other that compatible to installed a new windows.
In this way http://www.ultimatebootcd.com/ can help you to delete and create new partitions.
if you are an expert follow the steps for CMD prompt.
https://technet.microsoft.com/en-us/library/cc725797%28v=ws.11%29.aspx?f=255&MSPPError=-2147217396
If you have not formated your windows drive and have working windows OS then use EaseUS Partition Master
http://standaloneinstaller.com/download-easeus-partition-master-professional
to deleted all partition and convert GPT to MRT and then make new partition.
Finally you have well setup you pc for new installation windows.
Now i have successfully installed windows new OS instead of factory installed.
Hope that help you.