Detection of a non-visible character in an excel cell

Thank you for this response, which I already knew, but the CTRL End points to the last cell that encompasses all the data contained in your table, including cells with invisible characters. We then know that there is either on this row or in this column a visible element that needs to be deleted (deleting the row and then the column).
Don't forget to return to one of the visible cells, e.g., cell A1, and save the file. However, if there are several cells scattered throughout the file with invisible content, we have to repeat all the operations until we only have the desired data. It is also possible to search for a space with the criterion of an entire cell, and there we find all the cells that fall into this category. However, a line break in the same cell (also an invisible character) cannot be "entered" in the search area. Is there not a function that would allow me, like in Word, to make these kinds of characters visible? (like displaying formulas in cells instead of results)
Michel

Why start over line by line?
If Ctrl+End takes you to Z300 and your last useful cell is C5, you delete all rows and columns beyond C5 at once.
You'll have to do that manually; Excel can't know what's useful or not.

A macro to finish the job:

Sub clean()
 Dim pl As Range, c As Range
 Dim car, tmp, i As Long
 
 car = Array(8, 10, 13, 160)
 Set pl = ActiveSheet.UsedRange.SpecialCells(xlCellTypeConstants, xlTextValues)
 For Each c In pl
 tmp = c.Value
 For i = 0 To UBound(car)
 tmp = Replace(tmp, Chr(car(i)), " ")
 Next i
 c = Application.Trim(tmp)
 Next c
End Sub

The unwanted codes to be replaced with a space are listed in the car constant.
I've included Tab, CR, LF, and the non-breaking space.
This is complemented by the removal of unnecessary spaces.
The macro processes the entire active sheet.
eric