In WordPress Dashboard go to Appearance submenu and click on Customize.
After clicking on customizing you will in theme Customizer.
Here you have to click on Page Template than 404 Page
In Setting Here you can Hide/Show of 404 page.
Go to Customize -> Page Template -> 404 Page -> Setting
In WordPress Dashboard go to Appearance submenu and click on Customize.
After clicking on customizing you will in theme Customizer.
Here you have to click on Page Template than 404 Page
In Content Here you can Change Content of 404 page.
Go to Customize -> Page Template -> 404 Page -> Content
