The Expert Advisor closes all open and pending orders on the chart it has been launched at.
Simply apply it to any symbol chart to close all orders on that chat regardless of their amount. No other symbols will be affected.
After all deals are closed, the EA is turned off.
Suppose that you have a few pending orders on EURUSD, as well as an active buy on USDCHF.
If you launch the EA on EURUSD, only pending orders on EURUSD are removed without affecting USDCHF.
If necessary, you can close your position on USDCHF as well by simply launching the EA on the appropriate chart.