Is it a limitation that only one user can own (edit) a web map?
Please let me know if any workaround.
I believe the admin user could transfer ownership of the item to him/herself, make the changes, save it,and then transfer the ownership of the item back to the original owner if necessary.
Is this with the free account or with an organizational account?
An organizational account.
Yes, there is only one owner for an item. However, with an organizational account, someone with the role of administrator does have full control over all items.
Please let me clarify our scenario.
My supervisor and I have admin rights in the organization.
However, my supervisor cannot save the web map which I have ownership (only choice he has is save as).
Is it expected?
What privileges an admin has depends on how the role assigned to that member is configured. Likely, your admin is missing the Update privilege.
Turns out this is being limited by the arcgis.com application not privileges. I don't know why, but I'll see if I can find out. Bottom line, however, is that you can't save as an admin.
It's technically challenging for us to allow an admin to save a web map as its owner. Thus, we don't do it now. I think Tobias provides an good workaround to the problem in the post above.
Retrieving data ...