Remove unwanted columns/rows

I am using Office 2008 on a Mac. I have a sheet that uses 31 rows and 30 some columns for data, but the sheet shows 10,000 some rows etc. I have tried resetting the print area, cutting and pasting into a new document, search this forum. Command End brings be someplace deep but there's nothing there, when I try the Command arrow and delete all, I run our of memory.

Any suggestions?