Eraser
The eraser removes objects one at a time. Press E to activate it , then click anything you want gone: an atom, a bond, a text annotation, an arrow, or an atom decoration such as a charge, lone pair, radical dot, or orbital lobe.
What a click removes
The eraser checks small targets first, so clicking near an atom that carries decorations removes the decoration before the atom itself. The priority order is: charge, radical dot, lone pair, orbital lobe, then atom or bond, then annotation. Charges reset to zero; lone pairs and radicals are removed one dot group at a time.
Deleting an atom also deletes every bond connected to it. The reverse is not symmetric: deleting a bond keeps its atoms, except that bare unlabeled carbons left with no bonds, no charge, and no other content are cleaned up automatically.
Drag to erase
Hold the mouse button and drag across the canvas to erase everything the cursor passes over. Each object is removed once per drag, so sweeping back over an erased spot does nothing extra.
Alternative: select and delete
For bulk removal, switch to the Select tool, select the objects, and press Delete or Backspace . This removes the whole selection as a single undo step.
Either way, Ctrl+Z restores anything you erased.