Lame_Wolf - 12:59 pm on Mar 18, 2011 (gmt 0)

This site is catering to niche area and getting 50-70 targeted visitors daily.

I can go for a piss and when I return, i'd have had more visitors than that. The site sounds very young, so best to make changes now.

If I just remove, it'll generate 404's and lower my site's rankings?"

Well, if you are only receiving "50-70 targeted visitors daily" it's hardly a SERP worth chasing is it ? Not yet anyway.

410 will be extreme step because I lose all PR earned as well as hit's and links to that page.

I am guessing here, but as your site sounds young, and with so few visitors, then what are we talking about... PR1 ? PR2 ?

Stop trying to flog a dead horse.
Read the Google guidelines, read the Adsense TOS... Then learn them. It's your only way.