Typing a small character above a letter, a superscript, is an option available in nearly every modern word processing program. Superscripts are frequently used for references, such as footnotes and endnotes, as well as for common mathematical notations, and enabling or disabling a superscript is usually done via menus or by using keyboard shortcuts.
In most word processing software, the superscript command is located in the Home or Format menu. Most word processors also have keyboard shortcuts you can use to enable or disable superscripts, though these vary from program to program. One common exception is the Notepad program that comes with Windows, which does not have the ability to display superscripts at all.
In Microsoft Office, the superscript command is in the Format section of the Home tab, identified by the icon of a superscript above a letter. The keyboard shortcut Control+Shift+Plus Sign also toggles the superscript command. In Google Docs, the Format drop-down menu has the superscript option in it, or you can use the keyboard shortcut Control+Period. In the free OpenOffice software, superscripts are also available by clicking the "Format" menu, then "Character" and then the "Position" tab, or you can use Control+Shift+P.