Delete all Google Photos

paste_to_devtools_console.js

for(i = 1; i<=9999; i++) {
    console.log("Iteration # --> " + i);
    document.querySelectorAll('div[role=checkbox]').forEach(div=>div.click());
    document.querySelectorAll('div[aria-label*="Select all photos"]').forEach(div=>div.click());
    await new Promise(r => setTimeout(r, 3000));
try{console.log("Selected documents count for iteration [" + i + "]: " + document.evaluate('/html/body/div[1]/div/c-wiz/c-wiz[2]/span/div[1]/div/span', document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue.innerText);}catch(ex){/*do nothing*/}
    document.querySelector('button[title=Delete]').click();
    await new Promise(r => setTimeout(r, 5000));
    document.evaluate('//span[text()="Move to trash"]', document, null, XPathResult.ANY_TYPE, null ).iterateNext().click();

    //wait for new images to load
    await new Promise(r => setTimeout(r, 15000));
}

Thanks a lot. The last script given by @dcepelik mostly works, but I needed to change the '//span[text()="Move to trash"]' to '//span[text()="Move to bin"]' since the text has changed in UI.

Also, just a tip for anyone clearing their gallery. If you zoom out in the browser, it seems works faster as it deletes more images in every iteration. But zooming out too much caused issues where it was deleting too many images every time, and the trashing dialog wouldn't go away before it tried to delete more pictures, causing it to fail. So, experiment a little to find the sweet spot.