How to hide personal information like email address in one's profile, since I do not want my email to be seen by others?
This is detailed in several questions on Meta Stack Overflow, for example this one.
In general, the way to hide personal information is simply by not entering that information in the first place. Most fields of the profile are optional, so you enter only what you want people to see.
The email address is one of several exceptions. Your email address will never be visible to anyone except moderators. (And the SE moderator code of conduct prohibits us from revealing that information to anyone else.)