You can hide the singer's voice from the music files that cannot hide the voice in the computer.
By default, it will be saved with 2 audio tracks of singer + melody.
If you want to save only the melody without the singer's voice, you have to select the No Vocal option.
To save the output file, click Save Folder and choose the location you want to save (Default: Desktop).
If you are sure of the above preparations, you can change the file you want to change by holding down the mouse...