I want to delete only last version of back up from the cloud. How can I do it?
In the Duplicati Web interface, click your backup to expand all the options. Click “Commandline …” and change the dropdown to “delete”. Scroll to the bottom of the page and in the “Add advanced option” box, choose “version”. Type the number “0” in the version field to delete the most recent backup and then click the “Run ‘delete’ command” button at the bottom of the page.
Actually, I was just reading the description and it sounds like “0” is the default. So you may not need to specify a version if you want the most recent one deleted.