OK, the following assumes you have at least some familiarity with FORScan (
http://forscan.org). You will need to have an extended license to change configuration. There's a message that the extended license function was disabled in the US as of 2 days ago due to issues sending funds to Russia; but fortunately, the 2 month free extended license functionality is still working. Be prepared to wait up to 30min for the license key to be generated.
Start by connecting to your vehicle (icon on bottom left of the first screen):
After connecting to your vehicle, select 'Configuration and Programming' on the left, and select the GEM/SJB module. Make sure you choose the one shown, and not the 'As Built' configuration. Then click the Play button ('Run Service Procedure') at the bottom:
From here, select 'Daytime Running Lamp' and choose 'Edit selected' at the bottom. (BONUS: For those interested in enabling 'Dark Mode', disabling 'Welcome Illumination', and/or modifying your TPMS alarm values, they're also changed using this screen.)
This dialog is straightforward:
And Tada! You've either enabled or disabled your DRLs, depending on what you selected.
Don't forget to disconnect FORScan before unplugging your OBD adapter.
Click on the top left 'Vehicle and interface information' icon, followed by 'Disconnect' at the bottom.
Any questions, let me know.