assests folder automatically filled with preloaded images.

[arunbaby0]

I have removed all the unwanted images from the assets folder before doing the bundle serve. Still the images are somehow getting copied into the _site folder. Are there any settings to disable this? And how is this happening?

[mmistakes]

The theme doesn't have any images bundled with it so not sure. If you have a public repo I could take a look, otherwise I'm just guessing.

If you forked the theme you likely have files that should be removed. There is content in /docs for the documentation site and there is test content in /test. After that I would run Jekyll's clean command to clear out any cached folders and _site.

jekyll clean

[arunbaby0]

I am not sure about this: in gemfile, changing from
gem "minimal-mistakes-jekyll" , path: "../"

to
gem "minimal-mistakes-jekyll" #, path: "../"

solved my issue

[mmistakes]

Looks like you forked the theme... which gives you a Gemfile that is meant for developing the theme only.
I do not suggest forking the theme's repo. Instead following the installation instructions by creating a clean Gemfile. There are development files in the main repo that will cause you issues if you fork directly.