Disable External Sharing in SharePoint.

External Sharing can be a security issue if your users are sharing information with outside sources who should not have your company’s information.  

In this article, we will go through the steps that a global admin may take to stop external sharing for your domain.

Control sharing at the organization level in SharePoint

 Log in as a global admin to https://admin.microsoft.com and select “SharePoint” from the admin section. 

Inside the SharePoint Admin Center page, select "Policies" on the left-hand side, then select "Sharing" in the drop down.

On the "Sharing" page you should see two sets of toggles under "External Sharing" These toggles control the over all sharing setting for your organization. Please know you will not be able to give the OneDrive toggle a more permissive setting than the SharePoint toggle. This is by design.

Setting external sharing settings for a specific SharePoint site.

 Log in as a global admin to https://admin.microsoft.com and select “SharePoint” from the admin section.

In the SharePoint Admin Center select "Active Sites"

Select the site you want by clicking the circle next to the site’s name, then choose “Sharing” when it becomes available at the top ribbon.  

When the sharing pane opens in the you can choose your external sharing setting for this specific site then click "Save”