Most of the SEO plugins like Yoast and SEO Framework allow you to do that. But the feature is becoming useless because Google is appending the title by itself as a way to create site trust for the users. So, it is practically useless to try to remove the title tag coz google will still insert it https://support.google.com/webmasters/answer/35624?hl=en. But you can still try it.
the advice that GG has provided ( thanks GG ) covers it really well.
You can try editing your Post Meta Title using a SEO plugin. And see what happens but if google thinks it needs to add the Site Title then aside of asking in there forums its pretty much out of your control