Eliminating rows in Excel worksheet

I am using 1200+ rows in a worksheet, but there are more than 65,000 rows on
the worksheet and it makes it cumbersome scrolling up and down to make
changes. How do I get rid of the rest of the rows? I've tried highlighting
and deleting, but that doesn't do anything. Thank you,

Why don't you just highlight them, then right-click and hide them?