As discussed, the relationships are not cached in any way and are read from the cluster.
The way to clean them in case the ONTAP Cloud was removed is to make sure that the Cluster and SVM peering is removed from the remaining on prem.
Regarding the relationship creation seemingly in progress - It is a minor UI glitch. We have no way to know if the instance was terminated in mid action,
and during the next monthly Cloud Manager update it will be closed as failed.