Release #242, on June 23, 2022, introduced the ability to easily void a trade, essentially deleting the trade while maintaining the reporting data up to the void date.
On the TRADES screen, find the trade you wish to void, click the hamburger action menu and select VOID:
From there, you can update the void date and press SAVE when finished:
All valuation entries for this trade with a reporting date greater than or equal to the void date will be deleted.