Why would you remove one of the most important elements of on-page SEO? Even small adjustments of the text of the title element can seriously affect your rankings! I don't know what you mean by "tagline". If you mean the meta keywords, then do whatever you feel like, since the meta keywords do not have any effect anymore.
Seconded, don't remove the title. It does two things for you. 1 - Gives Google more text to search, and since the title is basically your thesis statement, they put more weight on its importance. 2 - Even if you don't get a first ranking in Google, the right title will attract more clicks regardless. How many times do you do a search and look only at titles, going as far as the tenth result to find one to click first? Good luck!
your question does not make sense you might want to be a little more detailed of what you have and what you want to accomplish examples always help
well i have a wordpress prosense theme blog i put a custom heaeder on it, I dont want the title and description tag showing up on it. I'm sure people must hide or remove these when they customize the header as i dont see many with ugly titles and descriptions on their custom headers.