pkiremove: 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/pkiremove - from package: pki-setup

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

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