MankDemes :
I don't know how to do it safely and easily without software. I need help!
Disconnect all drives except the target drive that will be the C.
Boot from your Win 10 install media. DVD or USB
When it asks where, select Custom.
You will be presented with a list of all existing partitions on that drive.
Delete each one, leaving one large blank space.
Let Windows install to that, creating what it needs.