If your phone is rooted, can it still do normal factory reset? Like you wouldn't notice if it's rooted or not?
Yes, but unrooting will require more than a simple factory reset. The process will depend on your phone model. Search your model and 'unroot' for instructions. Be sure the instructions are for your specific model and are from a trustworthy source, such as XDA. But if you were able to root your device, I assume you already know that.