Any audio editing/ recording software will be of use. Suggests to try FlexiMusic Wave Editor. Completely removing unwanted background noise is not possible but can be removed to some extend. Play your recordings in the software. Use "Noise Reduction command to reduce the unwanted background noise. To improve or equalize the volume of recording, from the menu choose the "Volume" in which, select the "Simple Compress/ expand" option to opt the percentage of the volume for the entire recording.
