No idea about getting rid of mould, but I suppose you can give em a spray with that stuff you use on shower screens and bathrooms.
Now I only use stuff that works. Been through a few of those so called waterproof Motorcycle gloves and irrelevant of price their just junk, except for
The BMW Pro Winter ones. So good I brought a pair and I'm no millionaire, but they cost a couple of hundred and their bloody perfect. Rode home in a Thunderstorm for 2 days and not a wet spot in the gloves
But for years and years, used to put over my normal everyday gloves a pair of them long chemical gloves you get from the safety shops or you steal from work. Just remember to take your gloves with you when you got to get em, so you can try on the gloves when you have your bike gloves on