Mould can be very difficult to remove from silicone sealant but there is a natural product that can do the job in 10 minutes ...

Waterproofing ... synthetic waterproofers are silicone-based, and non-synthetics contain natural waxes and oils like mink oil or beeswax. Both provide a strong seal against water — Eduard ...

Silicone sealant, the white waterproof lining found around showers ... Once suitably attired, fill an empty spray bottle with white vinegar and douse the mouldy area generously.