Sure, first unselect Linking and then click select a clip and Delete it.
Sounds like you got 8 original audio tracks from the HD cam and when downconverting it to 720, you got those same 8 again. How many audio tracks are really active? Was this captured over SDI to get 8 tracks?
If you have doubled the audio tracks, you can surely delete or not even import them onto the timeline when editing.