You can liquidate a stock by selling it in the stock market. Selling a stock in the market depends on a variety of factors. You cannot sell a normal T+3 trading stock on the very next day after you bought it. You would have to wait atleast 3 full days since you bought the share to sell it.
In case of Intraday - you have to sell the shares you bought at the beginning of the day before the end of the trading day
In case of BTST - Buy Today Sell Tomorrow kind of trades - You would have to liquidate the stocks that you bought today by the end of day tomorrow.
Liquidating a stock means - Selling it.