If you want to remove a page from the website entirely and don't want to keep a draft, you can archive it. Archived pages can be restored but are not shown in the page list by default.
While in the editing view for the page you wish to archive, click on More Options at the bottom then click on Archive. You'll be asked if you're sure you want to archive the page, click OK to confirm. This will remove the page from the draft site and the live published site.
Restoring an Archived Page
To view archived pages in the page list, click on the Pages tab and then on the Filter bar (directly to the right of the page list).
Within the Filter options, look for the Pages option (it will say All Pages), click this and select Archived pages, this will update the page list to show Archived pages.
To restore these pages, first click on one and then click the Restore draft button at the bottom of the screen. You can then make changes to the page and click Save & Publish to go live.