As Google announced HTTPS (Hyper Text Transfer Protocol Secure) site will get more ranking boost comparatively to HTTP. Accordingly, Webmasters start migrating their sites from HTTP to HTTPS.
According to “Barry Schwartz” from SEROUNDTABLE, “Would I recommend everyone do it for the ranking boost. Absolutely not. But maybe you want to consider it for other reasons outside of rankings – that is up to you”.
John Mueller of Google was asked if there is any reason to keep the HTTP version verified in Google Webmaster Tools or just let it go away. John said on Twitter you should keep it active because it can still pass back important errors you may want to see.
When I migrated over my corporate site, I kept and still keep, both sites verified in Webmaster Tools this way I can see how the migration went in terms of index pages dropping down on HTTP and increasing on HTTPS. Plus you can see your query reports change and of course pick up on any important errors.