There has been always slight confusion as to what of the 2 commands to use while destroying a cluster - cluster destroy cluster -f destroy
The difference between the two are
cluster destroy : This will clean out all the data on the cluster and wipe out all the configurations.
cluster -f destroy : This command does the exact same thing. Also it will bypass any check for any service on the node. It grants permission to destroy cluster even if zookeeper node is not accessible. Think of it as forcefully destroying the cluster.
Always make sure to reclaim licenses before destroying the cluster to follow best practice.
Licenses can be reclaimed via the portal or can also be reclaimed manually via SFDC.
If licenses are reclaimed manually following commands need to be run once they are reclaimed:
ncli -h true
ncli license reset-license