There is more information available on this subject at Machete on the English Wikipedia.

The Machete being wielded by the Master Chief in Alpha build of Halo: Combat Evolved..

The Machete was a melee weapon that was originally planned to be included in Halo: Combat Evolved. It was deleted before the final game was released; the final product has no melee-specific weaponry, the player can perform a 'pistol whip' or 'butt slam' attack with any weapon.

Deleted Material

Machete is part of the Deleted Material cut from the Halo series.

When developing Halo: Combat Evolved, Bungie faced numerous prototypes during the pre-production and considered cutting down to a certain number of objects for the final bit of Halo: Combat Evolved.

As such, many aspects of the story such as vehicles, gameplay, design, and story elements didn't make it into the final version of Halo: Combat Evolved.