One way...
Select each image to be removed while holding down the <ctrl> key. Then press the <del> key.
If you make a mistake, immediately press <ctrl-Z> (EDIT|UNDO) to go back, step-by-step.
Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the caret to the right of the Save Project button on the toolbar.