@ram_k
You are welcome. You can vote for this request in the top left corner, cause probably there is a solution for this, it just has to be implemented and released.
https://forum.inaturalist.org/t/limit-cache-size-or-allow-cache-clearing-for-apps/2059
and the results:
https://forum.inaturalist.org/t/limit-cache-size-or-allow-cache-clearing-for-apps/2059/45
‘‘2. So I suspect this is related - it will be interesting to know out of those users with lots of storage being used - do they mostly use the app to upload observations?’’
Your friends are also in this categorie, I presume?