kubectl apply --prune -f namespaces.json --dry-run=false

gistfile1.txt

namespace/user-af configured                                                                                                                                  
namespace/user-anm configured                                                                                                                                 
namespace/user-apo configured                                                                                                                                 
namespace/user-atm configured                                                                                                                                 
namespace/user-atu configured                                                                                                                                 
namespace/user-ers configured                                                                                                                                 
namespace/user-fd configured                                                                                                                                  
namespace/user-hwha configured
namespace/user-jbn configured
namespace/user-jbr configured
namespace/user-jda configured
namespace/user-jp configured
namespace/user-jsj configured
namespace/user-jsj-kubeflow configured
namespace/user-jth configured
namespace/user-kh configured
namespace/user-mabd configured
namespace/user-mb configured
namespace/user-mvs configured
namespace/user-pag configured
namespace/user-rk configured
namespace/user-shm configured
namespace/user-so configured
namespace/user-sps configured
namespace/user-thl configured
namespace/user-vn configured