If you beat any level with MAUL, SPARTAN or WARBLADE, go to the one you beat the level with and press A, B, X, Y, SELECT and START like crazy for three to five seconds. Doing so will remove the guitar music.
To skip the pain of getting past the first two levels, enter the password JKPWD. This password allows you to choose between WARBLADE, MAUL, or SPARTAN.
To skip directly to the temple level, enter the password CRTVV.