A square off is a trading feature in which a trader buys or sells stocks for a day in the hopes of profiting. By the end of the day, the traders should have closed their positions. Brokers offer auto square off, which automatically squares off positions at the specified time.

Equity Segment: 3:15 pm
Futures & Options Segment: 3:20 pm
Currency Segment: 4:45 pm
Commodity Segment: 11:15/11:45 pm ( Depending on Daylight Savings Time)

The position could have been squared off for a variety of reasons, including

1. Intraday trades will be automatically squared off at 3:15 pm for the Cash segment and 3:20 pm for the F&O segment.
2. If you lose more than 80% of your Available Margin, your intraday trades will be squared off
3. If you do not keep the required minimum margin in your account, your shares will be squared off four days after the shortfall occurs.
4. Square off will be performed on the next trading day if your shares purchased with Margin are down by more than 50% of your Funds balance.
5. Shares purchased through the Margin Product must be fully paid or pledged within 7 days, or they will be squared off.
6. If you have a debit/negative balance on your account, your shares will be squared off after 7 days.

Due to the upper/lower circuit in that stock, your buy/sell position may not have been squared.