Example:
011402
011403
011404

How can I remove 011 from a list of 10,000 prefixes?
If anyone can help out I would really appreate it.

Work with a copy of the workbook, so as not to risk messing up the
original.

One way is to select the column in question and use
Data Text to columns

In the box that appears, click "Fixed width" then "Next."

Using the ruler at the top of the next box, split the data the way you
want, then "Next."

Select the first column in the next box and click "Do not import column"
then "Finish."

The above assumes that all the entries are six text character and that you
want to remove the first three. If this isn't the case, please give more
details.

(I have Excel 2003.)