Hello ,
When you issue that command , the node where you have issued only come out of cluster . And the configuration will be the same as it was in cluster .
1. after this command , what is the configuration left on primary node and backup node .
> All configuration will be there as it was in cluster . Nothing gets erased .
2.what is the step is in order to reduce the downtime.
> Apply this command on the secondary node so that , that device only comes out of cluster and run as standalone . Then route the active traffic through this Standalone box and then issue the disable comand on Primary to bring this out of cluster .