To remove an unwanted feature, select the feature(s) that you wish to delete, then either select the Delete Selected Feature option from the right-click popup menu or press the DELETE key. Once you've done that, the feature is marked for deleted and will no longer appear on the display unless the Render Deleted Features option is enabled on the Vector Options tab of the Configuration dialog.
If you decide that you didn't want to delete
a feature, simple enable the Render Deleted Features option (see above)
to show the deleted features, then select the deleted features and select
the Undelete Feature(s) option from the right-click popup menu.
Render Deleted Features (Ctrl+Shift+D) - Selecting this option will render features that have been deleted from the workspace.