An ArcGIS Online administrator or the current owner of a site application item can transfer their site and its content to a new owner. To change ownership of a site and any items belonging to its groups, follow the steps to Change the owner in ArcGIS Online.
Ensure that the site is shared with a shared update group (edit group) and the new owner is a member of that group. Site owners can edit and manage a site in the workspace. The new owner must have the privileges to manage a site.
Change group ownership
To change the owner of a group that is shared with the site, follow the steps under Edit group properties and settings in ArcGIS Online. When reassigning group ownership, you do not need to remove items from groups that were added to the site using the content catalog.