You can still upgrade.  Download the Windows 10 Pro ISO and kick off the install from inside Windows. www.microsoft.com/.../windows10
I purchased an optiplex with a "downgrade" to windows 7 pro.  It came with the media to upgrade to windows 10 via DVD.  I have followed all of the instructions to change to UEFI boot and now i am stuck... ALL of the instructions say to boot to the UEFI CD and then click "Recover from Drive".  On this pc there is NO recover from drive option.  Can anyone tell me what i am doing wrong??
Optiplex 7040 > Windows 10 upgrade