Turn off and unplug the power source
Verify the circuit is de-energized with a multimeter
Use a resistor with appropriate resistance and power rating
Connect the resistor across the capacitor terminals
Hold the connection until the voltage drops to a safe level
Recheck the capacitor voltage with a multimeter
Repeat if necessary until fully discharged
Shorting the terminals directly should be avoided
Wear appropriate safety gear when handling capacitors
Discharge high-voltage capacitors only with proper procedures and training