Hello SharePointers,

Here are the below Pnp Scripts to enable /disable Modern Site Pages in Office 365/SharePoint 2016.

# Connect to your sharepoint site
$cred = Get-Credential
Connect-PnPOnline -Url https://[mytenant].sharepoint.com/sites/siteurl -Credentials $cred

# Disable Modern site pages 
Disable-PnPFeature -Identity B6917CB1-93A0-4B97-A84D-7CF49975D4EC -Scope Web

#Enable Modern site pages
#Enable-PnPFeature -Identity B6917CB1-93A0-4B97-A84D-7CF49975D4EC -Scope Web

Happy SharePointing 🙂