Remove volumes in the clean step.

docker/organic_build/Makefile

@@ -25,6 +25,7 @@ ifdef REMOTE_REPO
 else
 	@echo "REMOTE_REPO not defined, not removing from remote repo."
 endif
+	docker volume rm cargo-cache
 
 # NOTE: This target will write to folders underneath the git-root
 .PHONY: run

docker/organic_test/Makefile

@@ -25,6 +25,7 @@ ifdef REMOTE_REPO
 else
 	@echo "REMOTE_REPO not defined, not removing from remote repo."
 endif
+	docker volume rm rust-cache cargo-cache
 
 .PHONY: run
 run: build