"Saves for later" all Amazon cart items on the cart page. It will only remove visible items. You might want to scroll first to make more items visible. To use paste code in developer console (Ctrl+Shift+J or Cmd+Opt+J in Chrome) then press enter.

saveAllItemsForLater.js

function saveAllItemsForLater() {
	var query = document.querySelectorAll("input[data-action='save-for-later']");
	var last = query[query.length-1]
	if (query.length) { last.click(); }
	if (query.length > 1) { setTimeout(saveAllItemsForLater, 100); }
	else { console.log('Finished'); }
}
saveAllItemsForLater();

adapted from https://gist.github.com/MichaelLawton/ec73c321d62d1b4eaf0f51ca478ccd92