Launch your preferred digital audio workstation. If using a PC, double-click the desktop icon or click "Start," "Programs" and select the program from there. If using a Mac, click the desktop icon or open the "Applications" folder and launch from there.
Open the "File" menu, select "Open" and select the relevant session from the drop-down menu.
Hit "Play" and click the "S" icon on the top channel strip. "S" stands for solo. This function mutes all other audio, so you can listen in isolation. If the audio is vocals, double-click on the name box and rename it by adding "keep" to the end. This enables you to quickly identify the tracks you want when you come to make cuts.
Click "M" on the channel strip for each audio channel you don't want in the recording -- for example, "bass guitar." This mutes the audio. If you hit "Save" and burn the recording to a CD, the audio will remain muted but you can easily unmute it by clicking "M" again should you need it in the future.
Click "M" on the remaining audio tracks to turn off any unwanted audio, leaving just vocals behind. Alternatively, if you're absolutely sure that you don't want any of the backing music, click on each audio file to highlight it, then press "Delete" or if using Cubase, right-click the track and select the relevant removal option. The options differ slightly in wording, but effectively do the same thing. For example, in Cubase the option is "Remove Selected Track" (See References 4).
Launch your preferred workstation.
Open the relevant track. Hit "Play," listen to the track and rename the tracks that you want to keep. Click on the first audio file you want to keep. This highlights it and assigns subsequent commands to that track only.
Click "Send To" in the channel strip. Select "Bus 1." In audio, a bus is a mix channel to which you send multiple audio tracks. This enables you to mix those tracks using one set of parameters. So you can adjust the collective volume with a single fader, for example.
Click on "Bus 1" to highlight it.
Click "File" and select "Export As." Exporting a group of audio as a single creates a "submix." Select your preferred file type -- for example, "Wave Audio." When prompted, name the track "Vocal Submix." This separates the vocals from the remaining audio. You can now import the vocals into a new session.