You can delete tasks from 2 places:
- In the Task detail panel: Go on the 3 dots icon on the top right corner and select "Delete"
- In the task list: Right click on the desired task and click on "Delete".
When deleting a task that doesn't have children, you can always CANCEL the operation by clicking on the button of the same name in the green notification that appears. This notification is only visible during some seconds.
When deleting a task that has children, you will have to confirm your action and all the children tasks on the selected parent to be deleted will be deleted also. THIS OPERATION IS IRREVERSIBLE!!!