If I remove the date part from my blog URL using code in blogger, do I need to resubmit the sitemap to the Google search console? And I redirected my old URLs to new URLs. And does removing date from blog URL helps in SEO ranking?
do I need to resubmit the sitemap to the Google search console?
Yes. It might help Google to discover your new URLs quicker and will give you a more accurate representation of which URLs are indexed.
does removing date from blog URL helps in SEO ranking?
Maybe, but probably not. URLs play only a very small part in SEO ranking, the content is the primary concern. A date in the URL might deter a user from clicking a link if they think it is too old.
If the "date" is not significant to the content then it should be removed from the URL. If anything it will make the URL a bit shorter, which is a good thing from a user perspective.
An argument against having the date in the URL is that it can make the article appear out-of-date when it gets older, even when you may have updated the content (unless you implement a redirect to a new up-to-date URL - but that is complex and problematic). You can still include the published/updated date in the article itself.