Welcome to MrExcel - you can run this macro to see if it condenses your file.
<font face=Courier New><SPAN style="color:#00007F">Sub</SPAN> ExcelDiet()
<SPAN style="color:#00007F">Dim</SPAN> x <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Integer</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> LastRow <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> LastCol <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Integer</SPAN>
Application.ScreenUpdating = <SPAN style="color:#00007F">False</SPAN>
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">Resume</SPAN> <SPAN style="color:#00007F">Next</SPAN>
<SPAN style="color:#00007F">For</SPAN> x = 1 <SPAN style="color:#00007F">To</SPAN> Sheets.Count
Sheets(x).Activate
LastRow = Cells.Find(What:="*", After:=Range("A1"), LookIn:=xlValues, _
LookAt:=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
LastCol = Cells.Find(What:="*", After:=Range("A1"), LookIn:=xlValues, _
LookAt:=xlPart, SearchOrder:=xlByColumns, SearchDirection:=xlPrevious).Column
Range(Cells(1, LastCol + 1), Cells(65536, 256)).Delete
Range(Cells(LastRow + 1, 1), Cells(65536, 256)).Delete
<SPAN style="color:#00007F">Next</SPAN> x
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">GoTo</SPAN> 0
Application.ScreenUpdating = <SPAN style="color:#00007F">True</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
</FONT>
It is the code version of Oorang's suggestion.