The user can change the Location of the PermissionGroup entity as shown below:
POST/PUT
<ServiceRoot>/Sites(‘MySiteAlias’)/Plants(‘PlantA’)/PermissionGroupFolderChildren(‘PGRootFolder’)/PermissionGroups(‘PG1’)/Location/$ref
{
"@odata.id": "<ServiceRoot>/Sites(‘MySiteAlias’)/Locations(‘id of new Location to be associated with’)"
}