That works and is probably the easiest way to do it - select all the cells, and use find and replace to replace with "".
A little more work, but in case that doesn't work, you can probably do this using "text to columns.". Select the column containing data, and set . Or - as your delimiter. Then, choose NOT to export the column containing your delimiter. You'll then go from XXXX-XXXX-XXXX in one column to three columns containing XXX. To merge them back into a single column, use the function concatenate, and then copy and paste special values the results to turn them back into text.