@Mali Stane Thanks for posting in our Q&A.
Currently, there is no method that can delete app reports in intune portal.
Based on my experience, the text "Checked in. On next sync, this app will receive xxx" is helpful for us to check if the app protection policy works in the target app.
If you are still interested in this feature that delete old app record, it is suggested to post in intune feedback portal. t is a place to collect customers' requirements and problems. Here is the link:
https://feedbackportal.microsoft.com/feedback/forum/ef1d6d38-fd1b-ec11-b6e7-0022481f8472
Thanks for your understanding.
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