Go to the menu “Open another vault” (either using the command palette or the small icon at the left side of the app, close to the bottom). At the left of the opening menu, you find your vault name. If you click on the three dots right to the vault name, you can chose “move vault”.
Another option would be: move your complete vault (via your OS’s file explorer) to your iCloud folder and then open this folder as a new vault.