Diagnosis
Yeah, that LED is obnoxiously bright. Samsung calls it the 'Core Lighting', and it's on by default. You can't turn it off completely, but you can dim it to near-darkness.
How to Fix It
Press the joystick on the back to open the menu. Navigate to Settings > System > LED Indicator. Set it to 'Off in On Mode'. This will turn the red light off when the monitor is on. It will still glow white when the monitor is in standby.
If That Didn't Work
If the menu option is greyed out, make sure you're not in a specific picture mode like 'Console' or 'sRGB' that locks some settings. Switch to 'Custom' picture mode first.
Heads Up
There's no software setting to disable the standby (white) light. If even that bothers you, your only option is a small piece of electrical tape over the LED diffuser.