Assuming the source column starts in cell "A1", you can write in the first cell in the destination column:
=IF(ISODD(ROW(A1)),A1,"")
And drag it all the way down. If the column stats in another cell replace "A1" above with it. if the first source row is not odd, then change the function ISODD to ISEVEN.
In addition to the answers above, you can simply type in the fist cell {=B4}, and in the line below type {=""} to make a blank cell, then select the two cells, and drag below. There are many other methods to do the operation. Please see the picture below.