How to reset battery on 1999 nissan altima?

I've got an Actron code reader that reads and clears codes, about $40.

There's no way to "reset" a battery. If the Service Engine light is on, I would recommend getting a scan done to find out what the codes are. Resetting the light doesn't make the problem go away.

I take it you got a code saying a new battery was needed? And now it is replaced, you want to clear the code?