How to remove this? Because, i don't need this.
There isn't a way of removing the color-tag plugin using the UI I am afraid. One way removing it would be to move the file
/usr/lib/x86_64-linux-gnu/io.elementary.files/plugins/core/pantheon-files-ctag.plug into a new subfolder of
/usr/lib/x86_64-linux-gnu/io.elementary.files/plugins called e.g.
disabled. You would need to open Files as administrator to do this. You may find the plug reappearing if you update Files and it definitely will if you reinstall. A way of disabling unwanted plugins with a significant overhead might be a feature you want to request at https://github.com/elementary/files/issues