You can find the function under "Analysis Reports" and in the search view:
The feature 
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After a system is selected and the analysis is started, System Scout will generate a list of all InfoObjects which are no longer in use in the relevant BW - system. Therefore, unnecessary InfoObjects can be removed from the system to ensure a well-maintained and clear overview of all contents. Once the operation has been executed further manual analyses can be performed regarding the identified InfoObjects.
In the image below you can see the generated list of the unused InfoObjects:
Searched usages
This analysis function detects the usage of the following objects:
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