You might think that you need some kind of fancy partitioning software like Paragon Hard Disk Manager 15 Suite to free up disk space for the linux partitions.
You might also think that your linux installer will do everything for you automatically.
As it turns out, neither of the above are always true!
Sometimes, you need free space on your drive in order for the linux install (even Ubuntu) to be happy.
Fortunately, there is a very easy and built-in way to shrink a partition in all modern versions of Windows without any fancy software!