Renaming root Business Unit in Dynamics crm

 There is a surprisingly easy solution for this.  

Go to the business unit form (where you normally change the name of businessunit name).  

Notices "Parent Business" unit field is required. We just need to remove that validation. We can do that with a harmless script.

Open browser DevTools (F12) -> open tab Console -> Write or paste following script: -> and press enter.

Xrm.Page.getAttribute("parentbusinessunitid").setRequiredLevel("none")

The "Parent Business" field is no longer required!
Now change the name and press save.