diff --git a/src/vagrant/jupyter-bis/README.md b/src/vagrant/jupyter-bis/README.md
index 8294a53f8ce3c44bff687b9f873ee7b435af2aed..4be7e4122be0934c35d6c2bbf957cad8d9656ff3 100644
--- a/src/vagrant/jupyter-bis/README.md
+++ b/src/vagrant/jupyter-bis/README.md
@@ -83,6 +83,7 @@ This process describes how to upgrade your openBIS instance in your virtual mach
 10. do the openBIS upgrade: `bin/upgrade.sh`
 11. switch back to vagrant user: `logout` or CTRL-D
 11. start openBIS: `sync/initialize/start_services.sh`
+12. optionally delete previous installations (to save diskspace): `rm -rf backup/*`
 
 ## start openBIS and JupyterHub