Navigate to the page you want to remove by clicking it's parent pages. Single-clicking a page will open column on it's right side and list all it's sub pages.
When you see your page, do a right click on it. This will bring up a context menu.
To remove the page, click "delete". This will remove the page and all it's sub pages instantly.
Please note: Once you've deleted a page, it cannot be brought back (unless you have backups of your database). There will be no double check in the delete function.
In the upcoming versions, we will include the undo feature for delete