The dryness of a wine is determined by the sugar content of the grapes. That's affected by:
(a) the variety of the grape ;
(b) the type of soil in which the wine is grown ;
(c) the weather conditions where the wine is grown ;and
(d) the time at which the grapes are picked.
For example, a Chardonnay wine made from grapes which are picked early will be dryer than one where they're picked late, but Chardonnay grapes from hot sunny climate (e.g. California) will still produce a sweeter wine than those from a cooler climate (e.g. Northern France).
However there's still only a certain range of sweetness/dryness that canbe obtained from Chardonnay grapes. Wines from the Riesling grape will almost certainly be sweeter than a Chardonnay, whereas the Sauvignon Blanc grape will normally produce a drier wine.
However, to return to your question, nothing is added or taken away from a wine to determine the dryness. It's simply down to the qualities of the grapes from which the wines are made.
Chris