um_del_service: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/um_del_service - from package: umview

You may install the required package with command apt-get install {package}

Error in other languages:
um_del_service: bevel nie gevind nie
um_del_service: comandă negăsită
um_del_service: comando não encontrado
um_del_service: commande introuvable
um_del_service: command not found
um_del_service: käsku ei ole
um_del_service: không tìm thấy lệnh
um_del_service: komanda nerasta
um_del_service: Kommando nicht gefunden.
um_del_service: kommandot finns inte
um_del_service: komut yok
um_del_service: nie znaleziono polecenia
um_del_service: níor aimsíodh an t-ordú
um_del_service: no se encontró la orden
um_del_service: no s'ha trobat l'ordre
um_del_service: opdracht niet gevonden
um_del_service: parancs nem található
um_del_service: perintah tidak ditemukan
um_del_service: príkaz nenájdený
um_del_service: příkaz nenalezen
um_del_service: команда не найдена
um_del_service: командата не е открита
um_del_service: 命令找不到
um_del_service: コマンドが見つかりません