@Just i know i can lower the partition size within windows in disk management, but windows has annoyingly made an immovable file that makes it so i cant free up more than 290GB, which is quite a bit less than i want for my linux partition.
Rebooting Win several times after the resize, may/should allow it to be resized further.
What is the immovable file? Swap space perhaps? If so then this could be turned off .... or at least could in previous versions of Win.
I would strongly suggest you reduce from within Win, do a few reboots, and see if further reduction is available, before resorting to a 3rd party tool.
BTW ..... 290GB seems a huge amount of space for PCLOS .....
regards