How do I safely discharge a 3900 pF 3 kV (and 9 kV) capacitor?
If you were using 250V,350,500V,600V  1/4W rated resistors, you would need a safe string (in tubing) of 9kV/0.25kV= 36x 10Meg resistors with a value to determine the current and power limit.
There are also 1kV~10kV  resistors which might be a better choice.  There may be lossy materials that can withstand 10kV to function as discrete resistors that are mainly lossy insulators handled with neoprene gloves rated for this.
Always consider the datasheet safety sheet for a dielectric breakdown.

https://www.digikey.ca/en/products/detail/yageo/HHV-25FR-52-10M/2813022