How to clean off Mold on outdoor pillows ?

Make a paste with baking soda and a little water, scrub with a brush and rinse off. Baking soda kills moss and mold, but be sure to rinse well as it can be slippery if you use it on a deck or brick walkway.

Check to make sure its won't change the color or anything first. Wash it with bleach water to see if it gets rid of the stain. Rinse it thoroughly to make sure it all gets rinse out of the cushioning. Again, check to make sure it won't damage, and spray with vinegar to kill the mold/mildew spores. The cushion cover I would do the same way, but rinse off the vinegar, then wash in the washing machine with the curtains if they are washable in a machine. Cold water helps preserve colors better, so I would stick to the cool or cold water.

Vinegar vinegar vinegar. And some baking soda, a scrubbie and a garden hose. Get the items wet. Make a paste with vinegar and baking soda and scrub scrub scrub then rinse with garden hose and set in sun to dry thoroughly. Rotate and flip so they dry faster.

Here's a post that might help you - https://chascrazycreations.com/cleaning-yellowing-pillows-and-more/