Cadalyst tip reviewer Brian Benton shares two methods that can be used to remove formatting from AutoCAD text objects.
"AutoCAD users will often format multiline text objects from within the text editor. The first line will be made a bit bigger, or even a different font. Sometimes a different color is applied. That's fine, but when you try to change the style of the text or use Matchproperties, it does nothing. That's because the formatting changes within the text editor override the styles. It's similar to making a line's color red instead of bylayer.
"There are a few ways to try to fix this. Open the text in the editor. Select all of the text (press Ctrl+A), right-click, click Remove Formatting, then pick one of the three options given: Remove Character Formatting, Remove Paragraph Formatting, or Remove All Formatting. Remove All may be what you need.
"This should clear everything out. If that doesn't work, select all of the text (while in the editor) and copy (Ctrl+C). In Windows, open Notebook (a simple text editor that strips all formatting from text) and paste (Ctrl+V) the text as a new text object."