Google has removed their submit URL tool service. This tool allowed anyone to submit a URL to Google from google.com, as it wasn’t restricted to site owners only,
We’ve had to drop the public submission feature, but we continue to welcome your submissions using the usual tool in Search Console and through sitemaps directly.
— Google Webmasters (@googlewmc) July 25, 2018
Why Google removed Submit URL Service?
Google introduced this service to their some site owners who used it to submit URLs who were unaware of Google Search Console, it is likely the majority of those using the tool were SEO websites who want to submit pages they didn’t own. SEO websites could submit a URL for a page they have a link on, to get the link indexed and pushing PageRank faster.
Or they could use it to get a social media page indexed faster, often for reputation management purposes, such as a Facebook page or Twitter profile.
However Google found some users who were doing it on competitor sites to get spammy pages indexed and then file a spam report.
They do suggest the alternative ways for site owners to submit their pages via search console, either Fetch and Submit or via sitemaps, something most site owners were doing already. Their developer documents also suggest Pubsubhubbub for those using Atom/RSS.