Step 4: (optional) Make it safer
Solder a resistor across the leads of the capacitor. This will enable it to self-discharge in a controlled manner. You can use any resistance over 50Kohms, but the lower the resistance, the faster the circuit will decrease to a safe voltage. I clocked mine, at 100Kohms, the circuit went from full power (about 230V) to a more reasonable 20V in about a minute. 50Kohms makes the circuit safe in about 30 seconds.
Alternatively, you can completely remove the capacitor and never need to worry about stored charge again.