When an admin wants to delete an Item via Edit Learning History, the Delete option is not available.
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SAP SuccessFactors Learning
An item which does not have a Delete button, is a substitute for another item which has been completed.
From the example provided, note the Comments box which indicates that the Item the admins wishes to delete, is a Substitute item.
It's not possible to delete a Substitute item from the users Learning History, unless the main Item which was completed is deleted. Then the Substitute item will be deleted automatically.
In other cases, the Completion Status may also indicate that the item is a substitute.
Substitute item, Edit Learning History, delete, Completion Status , KBA , LOD-SF-LMS-ADM , System Admin, Global Variables, References , How To