Whenever we shared anything like site collection or subsite the email option is select by default and we have to uncheck it most of the time.
This post will help you to disable default “send an email invitation”
So lets get started :)
Browse to this location on your SharePoint server.
C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\TEMPLATE\LAYOUTS
And search for filename “aclinv.aspx”.
Edit in notepad or visual studio. Look for below labels and change the “Checked to False” it will be true by default.
After changing it save the file and refresh your SharePoint site.
Now, check the default “send an email invitation” will be disabled.
Note: This has to be done on all SharePoint Server and no iisreset or server restart is required.
Hope it helps :)
Happy SharePointing :)