The ERASE RECENT command erases anything which has been drawn on the current slide since the last time the current slide was opened or the PROTECT VISIBLE command was invoked. The general slide image which is part of every slide, things drawn on some previous occasion, and things protected using PROTECT VISIBLE, will all remain.
You can protect things you have drawn from being affected by the ERASE RECENT command by invoking PROTECT VISIBLE, or by using the right and left arrow keys on your keyboard to move briefly to another slide and back again. Clicking on the button with the eraser icon invokes the ERASE RECENT command.
Clicking on the button with the eraser icon while holding down the SHIFT key will invoke the ERASE ALL GRAPHICS command. This command erases all graphics you've put on the current slide, even ones previously protected.