Removing warnings

My site is hosted on domain iPage and I read in FAQ that i could only use the optimization function on JPG files. I tried to follow the methods to see if the other functions work but with no success, just jpegtran is installed without errors.

The optimization function in JPG for me is enough, however, the warning messages of optipng and gifsicle files is very annoying. Is there any way I can remove it?

Thanks!

https://wordpress.org/plugins/ewww-image-optimizer/