delete that collections from backend or You can redirect to another page
Refer this link....
My name is Alison, I'm the Customer Success Specialist for Ablestar apps. Our Link Manager app can help with identifying and correcting or redirecting any bad URLs that may be contained inside your site, or are being accessed by customers.
It can scan the Shopify store, and will list any bad links that may be contained inside product descriptions, collection headings, blog posts or other pages. You can use the app to help you correct these by pointing you to the page that contains them, or help you redirect them.
It will also list any 404 errors as they occur. These links could be from old emails or bookmarks people may have saved, old articles found on the web, or possibly old pages that Google or Bing still has indexed. Since you will may not have access to these URLs to correct them, using the Link Manager you can easily redirect them from the 'Visitor Errors' page.
If the 404 errors are coming from Google or Bing, you can also use Google Search Console or Bing Webmaster tools to request removal of the url. These are both free tools from Google and Bing that help you manage your web presence.
I hope this helps. Please feel free to reach out to us at email@example.com if you have any questions about how our app could help.