If that character isn't the prefix character ('1234 to force a text entry of
1234), then you can just do a Find and replace.
If that character is the prefix character and you want to convert text numbers
to number numbers, one way:
Select the column
Data|text to columns|Finish
Another way if the range isn't a single column:
copy an empty cell
select your range
edit|paste special|check Add
If this doesn't help, you may want to give an example of what you need--plain
text--not a workbook.