We installed white oak select flooring approx. 2 months ago (new construction). In the past few days a squeak has appeared in one board. Squeak is on the groove side and you can see the board flex looking really close. It appears like the groove is a little to large for the tongue. Boards on both sides are tightly nailed. Any suggestions on repairing this? Floor hasn't been sanded/finished. The house was conditioned prior to installation and flooring acclimated for approx. 2 weeks prior to installing.

That particuler board may have been mismilled. If you can access it from below, then drive a short screw up through the subfloor to suck it down. If this isn't possible, then that board will need to be cut out and replaced. Another option is to face nail it with finish nails and putty the holes.

Can you enlighten me on the best/easiest method of removing the board?

The best and easiest way is to hire a professional to do it. I'm serious. Unless you are a good carpenter, you may cause more damage to the flooring. A tricky repair.

The best way to remove a single board in the middle of a floor is to pay someone to do it who has done it.
IF that isnt an option, or you just want to get in there:

take a ROTOZIP, or Skill saw (circular saw)
Make two cuts down the middle of the board about one inch apart
Run your cuts as close to the end of the board as possible, without running into surrounding boards.
Make a final cut across the two vertical cuts.
NOw you can stick a flat head screw driver and pry off your bad board.
Be sure you dont ruin any surrounding boards.

THe trick is that when you applying upward pressure to the board, it will creek and not release from the fasteners and sub floor, thats when you tap the top of the bad board repetitively until it pops up, yes hit down on the board to get it to come up.

Now you have a open space where you will cut and route a new board to fit. Use GLue and a couple finish nails, you will need to remove the bottom of the groove side to allow the board to drop in, i

If you cut the board right, you will need to slam it in with a rubber mallet.

When you are done, drop to your knees and yell HALLELUIA, then drink yourself into oblivion. EIther koolaid, sprite, or your drink of choice.

Your Welcom
JAmal from Buffalo Wood Floors, no in Oregon not New York