creating a new user in Mac will it reset everything? I want to reset all my configurations trying to install MySQL &amp; other development stuff through the Terminal on my MacBook and start fresh. Because it was my first time doing this and I think I made lots of wrong stuff. 

So, do creating a new user will do this or I need to make a new "fresh" install for the OS?
Creating a new user will trash all the configurations that are stored in the old user's home directory (i.e. /Users/old_username)

This does not affect configurations done in the system folders(e.g. /usr/, /etc/, /Libraries

So you need to figure out if you configured mysql in your home directory or in the system folders.

Typically if you had to use your administrator privileges to configure mysql then it's stored in system folders.