I have seen a few mom's bring they unused formula to WIC Office's
Don't post it on a local swap site. It is illegal to even donate it. Give it to someone but don't tell them it is wic
You can give the formula to someone you know that needs it or you can post it on a local sale group on Facebook but list it as free
My wic office would not accept formula back. I donated mine to salvaltion army food pantry, they had no problem taking it