If you would like to use a formula, the TRIM
function will do exactly what you're looking for:
+----+------------+---------------------+
| | A | B |
+----+------------+---------------------+
| 1 | =TRIM(B1) | value to trim here |
+----+------------+---------------------+
So to do the whole column...
1) Insert a column
2) Insert TRIM
function pointed at cell you are trying to correct.
3) Copy formula down the page
4) Copy inserted column
5) Paste as "Values"
Should be good to go from there...