How do I remove the sidebar navigation menu from a page on my WordPress website?

To hide the sidebar navigation on a specific page:

1. Edit the page you wish to hide the sidebar on.
2. Click on any block for the top toolbar to appear, then click on the Options (three dots) button, and click on Show more settings. Settings should pop up on the right side of the screen and go to Page. Then under the Template drop-down, select Full Width Page:

3. Click the blue Update button to apply the change.

To hide the sidebar navigation for your entire site:

1. From your site dashboard, go to  Appearances > Customize
2. In the left sidebar menu go to Theme Layout Settings.
3. In the dropdown menu under the Sidebar Positioning section, select the "No sidebar option.” If you wish to change the position of the sidebar on the homepage from the bottom to the left of the page, this can be done using the dropdown menu under the Home Sidebar Positioning section:

4. Click the blue Publish button in the top right corner of the left sidebar once you are satisfied with your changes.

Note: Grandchildren menu items (children of children of menu items) will only display in the subnav (pictured below). When hiding the subnav, note that users will not be able to navigate to grandchildren menu items: