remove-shell: command not found

Have You tried accessing the binary with the full path?

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

[root@server ~]# echo $PATH

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/sbin/remove-shell - from package: debianutils

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