UPDATED: Remove n Characters from Front or Back v4.3
Remove n Characters From Front or Back v4.3 will let you delete a specified number of characters from either the beginning or the ending of the Song Name, Album, Artist, Comments, Composer or Show tag (or their "Sort" siblings) of each selected track. For example, delete the initial digits and the space from "01 First Track", "02 Second Track", and so on.
This latest version is now stay-open and floats above iTunes, has live track selection detection, re-orients preview stepper direction to abide selected tracks' sort order, can expand horizontally to enlarge Preview box, increases number limit from 24 to 60, and other minor enhancements.
Here's a screenshot of Remove n Characters From Front or Back in action during a tag editing session that also includes This Tag That Tag and Search-Replace Tag Text, which are also stay-open floaters: