Graphical User Interface
Press CTRL + R. Type regedit and navigate to
HKEY_LOCAL_MACHINE \ System \ CurrentControlSet \ Control \ SecureBoot \ State
0 = Disabled
1 = Enabled
PowerShell
Get-ItemProperty `
-Path hklm:\System\CurrentControlSet\Control\SecureBoot\State ` |
Select-Object UEFISecureBootEnabled