How to delete Docker image:tag from a Docker Registry?

deleteimage.sh

#!/bin/bash

# Check parameters
if [ $# -eq 0 ]; then
        echo "Login and password are missing (user:password)."
        exit 1
fi

if [ $# -eq 1 ]; then
        echo "Image name is missing."
        exit 1
fi

if [ $# -eq 2 ]; then
        echo "Image tag is missing."
        exit 1
fi

userPassword=$1
imagename=$2
tag=$3

token() {
        registryURL="https://PRIVATE_REGISTRY_URL"
        realm="$registryURL/dockerauth/auth"
        service="Authentication"
        scope=$1
        authURL="$realm?service=$service&scope=$scope"
        token=$(curl -ks -H "Authorization: Basic $(echo -n $userPassword | base64)" "$authURL")
        token=$(echo $token | jq .token | tr -d '"')
}

token "repository:$imagename:*"
tokenRepository=$token

dockerContentDigest=$(curl -sSL -I -H "Authorization: Bearer $tokenRepository" -H "Accept: application/vnd.docker.distribution.manifest.v2+json" "${registryURL}/v2/$imagename/manifests/$tag" | awk '$1 == "docker-content-digest:" { print $2 }' | tr -d $'\r')
curl -sSL -H "Authorization: Bearer $tokenRepository" -X DELETE "${registryURL}/v2/$imagename/manifests/${dockerContentDigest}"