xrdpwdadmin: 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/xrdpwdadmin - from package: xrootd-server

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

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