You need to edit just the required footage into a new sequence, then consolidate the resulting sequence. (just keep the bits of the clip you want by making new clips)
You do have a backup?
As you originally recorded directly onto your drives. I hope you also made a tape backup at the same time! If not I’d suggest backing up your media to a backup tape/disk first.
I would edit the whole original master clip onto the timeline
(It is easier to zoom into the footage. Long clips in the viewer are often difficult to navigate.)
Scan the first footage you want to keep then mark an in, use the razor blade tool, or V with the tracks selected.
Then moved onto the next footage required and then mark an out, or cut again.
Depending on what you did above you can delete the unwanted clip or delete between in and out X, if you go wrong Z is your friend.
Continue down your time line saving S from time to time.
Eventually you will end up with your shorter edited video.
You can then further tweak the joins and re-edit until happy.
The resulting sequence will still reference the SAME one original Master clip.
Please be careful with the following which you undertake at your own risk.
(You have a back up of your data?)
To just keep the required media and delete that unwanted, select your sequence in the browser then go into the media manager and COPY the media making sure that “include master clip outside selection” is DE-selected.
(Handles can be added which give a small amount of media before and after your selected ins in case you want to do a slight tweak in future.)
The top of the tool says what it is doing. If you do not understand please research further.
The green bars at the top will also show you want saving in storage you are making.
Select a destination and new sequence. (Ideally a different drive, then you can remove the original drive and make sure the new sequence and copied media is OK )
Always COPY your media (you will require even more storage) you CAN NOT get it back if you delete it.
There is good reason why it is sometimes called the media mangler.
There are some good video tutorials on the creative cow site on the media manager.
Good Luck
Steve