They put in 10 quarts?! Yikes. I've never had to use more than 7.5-8 quarts myself.
Yeah, get oil level down ASAP. I hope all is well afterwards, but overfilling engines is never good.
I always start by adding no more than I took out, or 1 quart less than I am supposed to. I do a quick check and make sure I am at the low end. Then I check frequently and top to the middle of the range. ALWAYS better a bit low than too high on oil.
Example: Just did my wife's Mini. It holds 4.75 quarts or so (can't remember exactly now). Despite checking recently and oil level being ok but a bit low, I later found somehow I only got 3 quarts out (???). I added 4 quarts only. I checked the oil and the level was smack in the middle of the mark.
Had I blindly added even 4.5 quarts I would have overfilled it.