Hi! I put an item in my wardrobe that now I want to sell. Is that possible or am I just stuck with it?

To remove an item from your Wardrobe, you'd press the on the top right of the item image. This will bring up a pop-up asking you if still want to remove the item or cancel, which you'd then press remove.

The only items that cannot be removed from your Wardrobe are Non-Tradeable items and items used in an outfit design.
If the items are used in an outfit design, then you'd just have to load that design, take off the item, and save it without the item in the design. You'd then be able to remove it from your Wardrobe.
If the item is not tradeable, you won't have the option to remove it from your Wardrobe.

I hope this explanation helps. ^-^

Yes, you can remove items from your wardrobe. :) When you go to the wardrobe, each item you own will have a red circle with a white minus sign located in the upper right corner of the item's square, and clicking on that will give you the option to remove it.

Edit:
Oops, I posted at the exact same time as someone else. XD Sorry for the redundant ping!