Mould? Mildew? On Polyester Fabric Clothing

Hi guys,

I found a pair of shorts I bought nearly 15 years ago. They’ve never been worn so maybe never washed. 100% polyester.

There’s some sort of stains (mould?) on a relatively small section.

Was going to try washing normally but thought I’d check first in case. Wondering if it can be removed & how?

Thanks