Mass MP3 audio file editor [closed]

Audacity will allow you to perform batch actions (called "chains") on any number of audio files. You'd load in the files, create a chain that trims the necessary number of seconds, and apply the chain to all the files you wish to affect.

dBpoweramp Music Converter (dMC) has a nice GUI and can batch process audio files and has a DSP Effects plugin which includes the ability to trim a fixed amount of time from the beginning or end of a set of files in any of its supported formats. Unlike SoX and Audacity (the other answers), it looks like mp3 is one of the supported formats.