How to remove all line classes from the app, after copying and pasting a bunch of text

How to remove all the line classes of the application, after copying and pasting a bunch of text, as shown, I want to copy a lot of text in the red area, but I want to remove the previously added line class, just let the text change Red class name, how do you do this? I tried to use removeLineClass and it doesn’t work.

If you paste a block of text, the lines that creates are new, and thus shouldn’t have any line classes associated with them. (When there are line classes, removeLineClass should definitely be able to remove them.)