Office 365: How to set user as Site collection administrator

An existing Office 365 User can be set as Site collection administrator using cmdlet SET-SPOUser. 

Following are the parameters.

Site
      Site URL, where the user needs to be as site collection administrator.

LoginName
      Login Name of User.

IsSiteCollectionAdmin
      Boolean, try or false, true for setting as administrator, while false for removing a user as administrator.

Syntax

Set-SPOUser -Site <siteURL> -LoginName <UserLogin> -IsSiteCollectionAdmin <true/false>