What you're looking at is a transaction history, that is, completed orders. You need to go to your SELL orders. The first screenshot you showed, the first option: "My purchase/sales", you have it displaying "BUY" offers. Click the "SELL" tab, and display all. You should see an offer there, probably something you made a while back when Bitcoin was still above $15k, and forgot about it. Cancel that and your Bitcoin should return to available balance

Like I said, I'm pretty sure it works like any p2p marketplace. If you make a sell offer, it just stays up unless you set an expiry or someone takes it.