pltcl_delmod: 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 CentOS possible default full paths are:

/usr/bin/pltcl_delmod - from package: postgresql-pltcl

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/lib/postgresql/9.4/bin/pltcl_delmod - from package: postgresql-pltcl-9.4

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

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