We have revamped our website and removed old dummy pages few month ago (we had around 600 and now 90 pages) Now our SEO guy complaining that site index goes down due to poor development. He says the chart is not going up because site is not get indexing. I said its just a number of pages from website and we can not expect it to go up.
Google will only index as many pages as you have available. So if you have 100 pages, Google might index something close to that number, but not any more than that. It will seek out the most content worthy pages and leave out as many low quality URLs as it can, such as duplicate content, empty pages.
If for some reason you removed 600 pages that are considered high quality, meaning good content, unique titles and descriptions, unique URL, etc. Then that was a bad idea and you will hurt for it.
But otherwise if you removed 600 low quality pages, then what you did was good but you'd have to wait a bit for Google to figure out what to rank you for again. Traffic will fluctuate and you'd have to advise your SEO guy to be patient, monitor the index, and ensure that few pages you have now are correctly optimized for search.