find /path/to/wherever -name "*.mp3" -delete

    find /path/to/wherever -name "*.mp3" -delete

    cd /path/to/wherever
    rm -rf *.mp3

?

  find path -iname "*.mp3" -print0 | xargs -0 rm -fv

  xargs reads items
  from  the  standard  input, delimited by blanks (which can be protected
  with double or single quotes or a backslash) or newlines, and  executes
  the  command (default is /bin/echo) one or more times with any initial-
  arguments followed by items read from standard input.

  --max-chars=max-chars
  -s max-chars
         Use at most max-chars characters per command line, including the
         command  and  initial-arguments and the terminating nulls at the
         ends of the argument strings.  The largest allowed value is sys‐
         tem-dependent,  and  is  calculated as the argument length limit
         for exec, less the size of your environment, less 2048 bytes  of
         headroom.   If this value is more than 128KiB, 128Kib is used as
         the default value; otherwise, the default value is the  maximum.
         1KiB is 1024 bytes.