Exclude markdown attribute

I have an older (pre-7.1)  website I designed. I had used a custom plugin to create markdowns for an accordion feature. I'd now like to use the markdown block to add color to the background of a text box. However, when I do that there is still a + on the right edge of the block and a line underneath, so I know that it's using the css for the accordion in the markdown. I don't have time to add the Squarespace accordion feature to the other pages of the website and remove the custom css I've put in. Is there a way to use a markdown for various types of needs? Can I exclude specific CSS or exclude the toggle and line for this specific markdown block? 

Can you share link to page where you want to remove +? We can check easier