package-uninstalls: 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/share/diskimage-builder/elements/package-installs/bin/package-uninstalls - from package: python-diskimage-builder

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

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