Acidity regulation of home made wine, berry wine or cider? What are methods to  regulate acidity of home made wine after it is become "a little bit too acid"?  

Somehow remove acid (especially acetic acid) or transform one acid to another (weaker, softer) with aging, temperature or food additives?

Once I have told with Riesling wine producer (even not small and from premium Rothenberg area) and he state it very clear : they regulate acidity not each season but quite often... But that time I was not interested in how they do it.
First thing, pick up a basic winemaking book. All of this is covered in there. 

If you have an Acetic acid problem, then you have vinegar not wine. 

If you just have high tartaric acid, you can do a two things. Cold stabilization and potassium bicarbonate. Cold stabilizing is putting the wine in a freezer at about 25 degrees for a couple of weeks. I usually do this naturally on the coldest days of the year. Tartaric acid turns into tartrate crystals and sink to the bottom. Also, you can add Potassium Bicarbonate and it reacts with tartaric acid and reduces it. You'll have to do some research here. 

If you have a malic acid problem, then malolactic fermentation is a way to turn the harsh malic acid to lactic acid. Again, consult a winemaking book to figure out the details.