We don't recommend this change because of the amount of debt you will incur with each new release.
However, technically you can, you will just need to remember with every upgrade new features may not be accesible until you manually add additional information like roles or set new configurations to this user for items to work out of the box. Also, make sure that all configurations are updated properly to point to the new user.
Is there a specific reason you want to change the user?
Thanks Kelly. The reason that we were inquiring was because we use active directory integration for authentication. The account has gotten locked out when testing components in our development environment (such as custom web services). This then impacts production because the two environments share the same account.