What will happen to my ranking if I delete some pages?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Ulvis Bernāts: That possible be negative effect of web page ranking if web page index of google better forward new page same info or page was closer info..
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  Rienzi Mosqueda: No longer of use meaning not ranking zero traffic?
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  Ilya Pushkarev: correct, they dont bring much results
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  Doug Betensky: Rienzi Mosqueda it won’t hurt to first make sure you aren’t deleting pages that might have links to them even though they have low to no traffic. Forwarding is a good idea if it makes sense on the site like Ulvis said.
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  Rienzi Mosqueda: Doug not at all. If you are linking to a page that google deems useless, what’s the point? Of course you are to audit make sure you’re not actually removing pages that serves a purpose for users like manuals etc.
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  Doug Betensky: Interesting perspective - hopefully we are in agreement, not sure. You are ok with the idea of checking backlinks to a page and seeing if it makes sense to 301 that page to a relevant page right before getting rid of that page right? So, if you have a product page, and it`s "no longer of use" "does not get any traffic" and you found that you got a link to that page from a quality source website, would you be open to redirecting that page to a relevant Category page? Let`s say that link was from a Manufacturer pointing to where someone can buy that exact product online, and then, you need to get rid of that page, so you redirect the product page back to the Category or Brand page.Just a thought.
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  Rienzi Mosqueda: Doug You are singling out a scenario where in reality you actually have to start from top to bottom not bottom to top. But yeah you should do that, but for the most part deindex deadweight pages and remove all internal/external links.
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  Doug Betensky: Rienzi Mosqueda thanks for your response.
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  Rienzi Mosqueda: Doug No worries. Always a pleasure. :)
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  Sam Mah: Check these pages on the search console before you delete them. Maybe you can add some internal link juices to those pages or write a better Title tag