This quick tutorial will show you how to remove the “Sent From Windows 10” message displayed in the Windows 10 Mail App.
Open Mail. Look for the “cog” (or “gear”) icon and then click/tap it. By default, it’s located at the bottom of the left column (see screenshot below).
This will bring up the Settings panel. Select Signature from the list.
You can disable the signature entirely by toggling the Use an email signature option to Off – or you can click in the text box and change the signature to something more personal for single account or apply to all accounts.