How to disable resizing of images to different resolutions.

This plugin does not do resizing. WordPress creates 3 resizes by default, if you want to change this, I recommend this article: https://www.wpbeginner.com/wp-tutorials/how-to-prevent-wordpress-from-generating-image-sizes/

Thank you for your immediate response. But, I am not getting just 3 resizes of the images. I am getting like 10 resizes of the same image. that’s the problem

Those are from your theme or other plugins.

Now I think, the culprit is my theme. because when i change my theme to twenty fifteen, i only get 1 resize of the image.