Unable to remove left navigation from a SharePoint Page. (Do not want to remove it from the site.)

I have a SharePoint Online page created with a template, which I cannot remove the left navigation pane from. (I can edit the list of links, but I want to remove the whole pane completely.)

I’ve tried to follow tutorials online suggesting I add a Content Editor Webpart and include scripts that will remove the left pane, however I don’t have the option to add a Content Editor Webpart on this page. (It doesn’t show the ribbon for the page, so only have the “Add A New Webpart” plus sign in the middle of the page to work with.)

I’ve even copied this webpage to a test site, and changed the site layout to Oslo, rather than Seattle, however the left navigation still shows.

Ideally I would like to remove the left navigation panel from this page only. Not from the entire site.

Thank you for any assistance you can provide.