This is a simple script to find and remove entries from OnTab

RemovePageOnetab.js

function triggerMouseEvent(node, eventType) {
  const clickEvent = document.createEvent('MouseEvents');
  clickEvent.initEvent(eventType, true, true);
  node.dispatchEvent(clickEvent);
}

// This is a helper that you can use to remove duplicate entries on a OneTab page.
// Use like this:
//   const url = "https://www.zeit.de/index";
//   removeDuplicatePages(url)
function removeDuplicatePages(url) {
  const pages = document.querySelectorAll(`[href="${url}"]`) || [];

  if(!pages.length) {
    console.log("Couldn't find any page.")
    return
  } else if(pages.length === 1) {
    console.log("Couldn't find duplicate of page.")
    return
  }
  
  console.log(`Found ${pages.length} duplicates. Removing ${pages.length - 1}`)
  
  [...pages].forEach((page, index) => {
    if (index === 0) return // keep first element
    const closeButton = page.parentElement.querySelector('img[src="images/cross.png"]');
    triggerMouseEvent(closeButton, 'mousedown');
  })
}