wouldn't have been set by the manufacturer, assuming you purchased it new then you've set it at some point.
To get the first point out the way... setting a BIOS password and then forgetting it is a very daft thing to do, there are several computers about which it's impossible to clear the password once set and a forgotten password can render the computer as scrap.
First thing I'd check on that is look under the memory chips by removing the panel on the bottom and then remove the memory, some acers have a little gold pad that looks like interlocked 3s hidden under there, you short across the pad with a screwdriver and it clears the bios.
If yours hasn't got the reset jumper pad on it then you will have to take it apart until you find the BIOS battery and either remove it for 1/2 hour or short it out if non-removable.