Wordpress website loading image which is not present in my website

So my wordpress website takes a lot of time to load pages. A problem that many of us face. I used GT metrix to check my wordpress page and then checked my website waterfall. One thing i saw taking more than half time of my page is an image which is not uploaded in my website.

check this image of gt metrix waterfall

its an image when checked is an image which i have not used in my entire webpage. Also i could not find where is this image used. Same thing happens in different pages that has different images to it.

I deleted one image from my media but now when i check the gtmetrix waterfall i get a 404 error code which means its still trying to load that image and i cannot find it.

This is a theme which i had purchased and its not a popular theme like divi or ocean and hence could not contact the support.

1)How to check where a particular image is used in my webpage using the media library (Can we do that) 2) How to find out and remove this image? or atleast is there a way where i can delete the image from the library and hence my webpage should not look for this image waste its time instead of getting a 404 code

Thank you