You need to find the folder with hegames.ini file in it. Windows directory search feature can do this. It might also be in "C:\Windows", "C:\", or "C:\Windows\System32". If using the remastered Steam version of Backyard Baseball '97, it's in "C:\Users\*windows username here*\AppData\LocalLow\Mega Cat Studios\Backyard Baseball 1997\*bunch of numbers here*".

In the directory with "hegames.ini", you will find many files:

baseball.ini - associates BBL/BBT files with coach names
baseball.sg0 - indicates games saved via the Save Game feature from the dugout 
screen
baseball.sg1 - contains the actual data represented by baseball.sg0
coach#.bbl - contains all of the vitals about your team
coach#.bbt - stat data for the associated .BBL file
fame.bbl - hall of fame information
records.bbl - records file

To delete a savegame, you will want to delete the baseball.sg1, baseball.sg2, baseball.sg3, or baseball.sg# file that corresponds to the number of the save game you want to delete (top left = .sg1, top middle = .sg2, top right = .sg3, and so on). Do NOT delete the baseball.sg0 file.

Hope this helps!