I am noticing the appearance of several numbered directories in my Master site directory.
They are named "installation_to_delete", "installation_to_delete_1", "installation_to_delete_2", etc. Currently there are four directories.

It would be good to know what is creating them and to confirm that I can indeed delete them?

I did uninstall the patches a few times lately so that I could update JMS. Was that the cause?

Thanks!

When the JMS patches are uninstalled, joomla requires that the /installation directory is removed to give access to your website.

In JMS, we prefered renamed the /installation into /install_to_delete_XXX
to allow you restoring the directory in case where you would need it.

When using a "localized" Joomla (french, german, ....), the /installation directory may contain some specific languages customization and we prefered to give you the opportunity to restore that instead of installing the default english one.

The name "to_delete" means that you can delete those directory if you don't need to restore them.

In the JMS patches, when the /installation does not exists, it gives you the possiblity to rename an directory for the restore or you can use a FTP or other tools to do it.