Removing underscore / hidden parameter from spfile in 19c

Hi

We have a couple of 19c databases that for some reasons have a bunch of underscore / hidden parameters

We are trying to remove those. Here is an example here

alter system reset "_always_anti_join" scope=spfile sid='*';

System altered.

But when we did the show parameter or executed select name from v$parameter we are still seeing this parameter in there

We even bounced the database but it did not help at all. We are still seeing this parameter in the v$parameter file view and also using show parameter

How can we completely remove these hidden / undescore parameters from the database?