Why can't the index.dat file be deleted?

Users in the water month asked: A colleague asked me to help her clean the C drive, I know that cleaning the C drive is mainly to clean up the IE temporary folder, I cleaned up the temporary files, I found a name The file index.dat cannot be deleted. I have tried many methods. Why can't I delete this file? Online Q&A link: http://sos.45it.com

index.dat is an IE cache index file that records information such as URLs, access times, history records, etc. accessed through the browser. It is actually a copy of the contents of the cookie, history, and IE temporary files. Since index.dat is a system protected file, it cannot be deleted.