1. you don't need downtime to clear that deprecated parameter on standby. just change in standby pfile or spfile would be enough
2. do you mean you want to stop auditing on standby totally?
I have two minor issues.
1. I have one deprecated parameter in a standby DB ver 11g (background_dump_dest). I need that cleared provided it does not require any downtime of the primary database.
2. Audit files are continually being written to the adump location. I need these to stop - again, provided it does not require any downtime of the primary database.
1) No downtime needed for modifying that parameter.
2) If you are going to stop auditing, you would need to modify the parameter that controls it, AUDIT_TRAIL and that's a static parameter ergo, you would need downtime.