You may close your current position via 2 methods: 
 

1. Close your current position by clicking on the Close By "Limit" or ”Market" icons and follow through on the request.

2. You may place a new order in the opposite direction of your current position (eg. current position 1 BTCUSD Short, to close the position, place an order for 1 BTCUSD Long). The position will be closed once the order has gone through.