Since the season has started, ive gotten the continuous flow of emails from my assistant about practice plan adjustments.  As im still a bit new at all this, im kind of at a loss as to what to do. 

William Wright is my starting PG.  Ive gotten emails telling me we are wasting time on his jumpshot, dribbling, passing, and free throw shooting.  Seeing as passing and dribbling are the main neccessities for a PG, im at a loss as far as what to change is practice time allottment to. 

Is there a minimum to keep practice time on something so the players skill dont diminish and what should I be changing his practice time to?

Change his PER to 3 and the other maxed stuff to 7.  Increase his time spent on footwork and start seeing if you can get him to improve in REB.

You may even try putting some minutes into LP. That now plays a factor for guards scoring inside the arc now.

I would put more time into his footwork first and conditioning second.

Look at your 'Player Thoughts' Email that you got at the beginning of the season.   Any skill that is listed as 'low' is pretty much maxed out. Skills that aren't mentioned at all are considered 'average potential' and should improve with practice.  Skills that are listed as 'high' improve the most, unless they are currently really low (less than 10)

Sometimes, usually with a senior, all the categories have been maxed out. 

If a player is maxed out in a certain skill (not counting PE, LP, or FT) and receives a good amount of playing time, then reducing those practice minutes to 2 or 3 probably won't result in them losing/regressing in that category. At least, it hasn't for any of my players.