30% bleach and 70% water. Scrub one side at a time let sit for a couple minute scrub then rinse do the other side then Soap the whole top and scrub to get rid of the bleach, after you wash the whole car put a top conditioner on it... It should look brand new.
My current top is tan Ive done this like five times since Ive had my car, A little color will come off the top due to scrubing and age but you won't notice any discoloration after the conditioner. The threads I can't really say I know the sun will destroy the threads, Myne were already worn So I used spider wire (braided fishing line) to replace the threads.
If you don't feel comfortable using the much bleach then use less. I think it depends on how bad the mildew is.
It also helps not to park under trees especially when it rains.
ok thanks everyone..im going to wait before i really start getting working on cleaning it cuz i live in fl and it looks like we might a few more storms coming this way..lol