How to remove Windows 7 Professional computer from domain to workgroup and remove all previous accounts belonged to domain?

Addendum:

Note: I attempted number 2, but was getting some errors like folder is shared etc. Thought i might not be doing it correctly.

What is the correct way to do it?

Removing a computer is just a matter of logging on with Admin privileges and going to Control Panel > System > Advanced system settings > Computer name.

There is one major caveat.

Make sure there is a Local Account that is active, you know the password and is an administrator. Joining a domain by default disables local admin accounts so leaving the domain can leave you with no working admin account. ( I have been caught out by this)

The message would indicate a domain user has shared a local folder either as a domain policy or individually. Click on Start, rt click Computer and select Manage. Under System Tools > Shared Folders > Shares you should find listed the active shares.