Hi ganesan, it's good to see you
again!
I agree with each of our member-friends whom have already given you, in my opinion, the very best & safest advice with how to approach registry cleaning.
Whether you'll choose to clean (or not) CCleaner is truly a favorite software among many more than our very own brethren here on MT.
In fact, before I found this thread I'd run both a system cleaning, & a
wipe of all
free space remnants (found under "Tools") for an external flash drive that I'd formatted (completely erased). I did not clean the registry, but have once or twice before, and only with CCleaner!
All I shall add is recommending their portable version which can become a part of the practice of keeping one's computer's system lighter by keeping certain apps separate from your system. I do this mainly with browsers, but also with CCleaner!