Check out these easy tips on how to remove mold from caulk. It works great to remove mold from shower caulk.
Materials List:
Bleach (Any brand will work)
Old Toothbrush
Baking Soda
Disposable cup
It’s a pretty easy process to remove mold from your shower caulk. It just takes a few things you probably already have around the house and about an hour of your time. 
To start you will need an old toothbrush, a disposable cup, Baking Soda, and Bleach. Mix about 1/2 cup of bleach with about a cup of baking soda in a disposable cup.
You may want to do just a little at a time of each. The amounts you will need will vary based on what kind of bleach you use. You will want to get your mix to the consistency of toothpaste so it will stick to the moldy caulk.
Once you have it mixed to a thick paste then use the old toothbrush to apply it to the caulk that is moldy (You will probably want to spot test in on a small area first to make sure it doesn’t damage the tile). Make sure it is on thick enough to fully coat the caulk. Set a timer for about 30 minutes and then just let it sit. It smells really strong so you may want to turn on a vent in the bathroom or open a window.
After 30 minutes check on the bleach mixture and make sure that it is still fully covering the caulk. Add some more bleach mixture to the caulk if needed. Then set a timer for about another 30 minutes.
Once the bleach mix has set over an hour then you can use the toothbrush to scrub the caulk for a minute or two. Then use warm water to wash away the bleach mixture. Make sure you get all of the bleach mixture off of the caulk and fully washed down the drain.
If you still see some mold on the caulk you can repeat the steps a second time to get rid of everything.
