Remove first image tag from {body}

Manipulating string content to find HTML tags isn’t ideal; can you describe why you are wanting to do this? That may give someone an idea for a better solution than what you’re trying.

I am using the main image as top image, and the same image with different dimensions are in body text too. I want to hide that without all articles.

I would recommend adding a File field to your Channel, and possibly an Image Manipulation for the resized version. Then you won’t be using a plugin or PHP to try to perform regex on a string. The output would be as simple as:

Full size:

{news_image wrap="image"}

With a “Small” constraint defined:

{news_image:small wrap="image"}

And simply omit this variable from your tags when you don’t want it to appear.