A self-lockout stops you opening new trades for a period you choose. It is there for the moment you know you should stop but would rather not rely on willpower.
You will find it on the Risk Management page in the terminal. There is also a lockout button in the terminal top bar.
The modes
Timed. Locks for a set period, chosen from preset durations.
Session. Locks around a start and end time in a timezone you pick, so it repeats with your trading session rather than a countdown.
Trade clock. Blocks new exposure while still letting you manage and close what you already hold.
What happens when a lockout starts
Every mode except trade clock flattens your open positions when it begins, so you will be asked to confirm before it applies. Read that confirmation: it is the point of no return.
Trade clock is the exception, and the reason it exists. If you want to stop taking new risk but still work an open position to a sensible exit, that is the mode to use.
You can always close a position
No lockout ever traps you in a trade. Close, reverse, cancel and flatten stay available for the whole duration. A lock is about stopping you opening new exposure, never about preventing you from getting out.
Lockouts your firm applies
Your firm can also lock an account. Those work differently in two ways: you cannot remove them yourself, and they always carry a reason, which you will see on the account. They may be timed or open-ended.
If you see a lockout you did not create, check the reason shown before contacting anyone. It usually explains itself.
The one you get automatically
Breaching your daily loss limit or daily drawdown locks the account for the rest of the trading day. That is not something you set, and it lifts on its own when the next session opens.