Bitcoins price is based on supply and demand on the market.More demand higher price more supply down price.Yes you can manipulate bitcoins price if you hold a huge supply or supply that may be enough to sell or buy in the current market status
by regulating demand and supply that means you can manipulate the price of bitcoin. but this time because bitcoin users have very much of course to manipulate demand and supply has been very difficult dude
Adjusting the price of bitcoin is just as impossible as regulating the demand of millions of people. Therefore, I am sure that you can not manipulate the price of bitcoin.