Hmmm… I see that in the docs, it says Active scan must be enabled for the devices we both use, however I do not have that option checked, and my device readings are picked up just fine in Home Assistant - FWIW, the batteries (rechargeable AAAs) last about 6-8 months.
Unfortunately this functionality has not yet been implemented. For the time being, the only way that existing long term statistics can be deleted seems to be direct database manipulation.
Fortunately one only has to remove the relevant row from the table named ‘statistics_meta’.
The row you need to remove is the one where you see your entity in the column named ‘statistic_id’
There are many discussion and polls in the forum regarding this lack of functionality.
[1] Long term statistics (how to remove from database)
[2] Remove statistics of disabled (not deleted!) entities from recorder
[3] Ability to clear (long term) statistics for excluded entitites
[4] WTH is it not possible to delete long term statistics for entities using services
Items 2, 3 and 4 are polls/votes for this feature request - please vote for them to encourage the developers to implement the ability for users to delete long term statistics for entities they have decided to exclude from recording.