OLD My Book Essential: (Help!) Basic Question on Available Space

I looked all through several threads, but I can’t find an answer to what is (prob’ly) a Newbie-type question…
I’m still using my over 10-yr.old W.D. My Book Essential 750GB USB 2.0 3.5" External Hard Drive.
Do the older back-ups within the 750GB drive accumulate and use up space that could be freed up by deleting said older back-ups?
(Thank you in advance; I’ve spent a lotta time spinning my wheels 'cause of this!)