disk space full

[Danny_111]

in task manager all my disk space is being used up by "System" and my computer is really slow. how can i lower the disk space back to normal I have a windows 8 my drive capacity is 932 gb

 

[USAFRet]

in task manager all my disk space is being used up by "System" and my computer is really slow. how can i lower the disk space back to normal

Any advice would require knowing a few specifics.
Primarily, what OS and how large is this drive?