How can i reduce the capacity of a Parallels disk?

I have m1 mac and parallels 17 editions and i have some problems I have only 256GB disk space for my mac. In usual my parallels disk takes 70 to 80 GB. But the size get bigger and bigger every time i use my virtual machine even though I delete unnecessary files regularly. When you look at the snapshots i attached my parallels disk takes almost 106GB but my actual space i use is only 70GB

When i look through the internet to search for an answer. Some threads said i can resize my parallels disk from advanced settings of hard disk but my hard disk starts from 256GB

whichis same as my disk size of mac. i'm going to buy some portable ssd shortly but i have to use my virtual machine right now. How can i reduce size of my virtual machine?