You talk to the stoneman and he makes you do stuff if you want him to remove it. If you've already erased his existence (storyline stuff) then get a hypno-mask to latch on your head then go into your inventory and use purple magic crystal
Not all of them are dead ends, certain paths leads you to colored buttons that removes walls with corresponding colors. Try the paths to the south of the blue circle
Try downloading the newest version here
https://f95zone.to/threads/the-agni...rsed-dungeon-v1-02-b-flat.72868/post-10648882
From the looks of it, saves from beta versions simply no longer work