Is there a way to clear application availability and statistics without deleting and re-assigning the template? I'm looking to truncate the table for a specific APM ID.
This could be done through the SQL database, though it is not officially supported in any way. This is mostly because if done incorrectly it could result in irreparable damage to the database. The only officially supported mechanism as you describe would be to delete/remove the application from the node, then reassign it back.
I have a dev system that I can test this method on first. Do you know what tables I need to look at?