AWS Identity and Access Management (IAM) 是 AWS 的一项服务，可帮助您安全地控制对 AWS 资源的访问。而清理不必要的 IAM 角色是 AWS 账户管理中的一个常见问题。

要删除不需要的 IAM 角色，可以使用以下 Python 代码示例：

import boto3
iam = boto3.client('iam')

# 列出正在使用指定 IAM 角色的实例
def get_role_instances(role_name):
    response = []
    for profile in boto3.session.Session().available_profiles:
        credentials = boto3.Session(profile_name=profile).get_credentials()
        ec2 = boto3.resource('ec2', region_name='us-west-2', 
                             aws_access_key_id=credentials.access_key, 
                             aws_secret_access_key=credentials.secret_key, 
                             aws_session_token=credentials.token)
        for i in ec2.instances.all():
            for tag in i.tags:
                if tag['Key'] == 'Role' and tag['Value'] == role_name:
                    response.append(i.id)
    return response

# 删除 IAM 角色
def delete_role(role_name):
    # 首先，查找 IAM 角色的路径，这在后面删除角色时会用到
    response = iam.get_role(RoleName=role_name)
    path = response['Role']['Path']
    
    # 接下来，查找 IAM 角色的策略以及附加的访问密钥和用户
    attached_entities = iam.list_attached_role_policies(RoleName=role_name)['AttachedPolicies']
    response = iam.list_role_policies(RoleName=role_name)['PolicyNames']
    inline_entities = []
    for policy_name in response:
        inline_entities.append(iam.get_role_policy(RoleName=role_name, PolicyName=policy_name)['PolicyDocument'])
    response = iam.list_role_inline_policies(RoleName=role_name)['PolicyNames']
    for policy_name in response:
        inline_entities.append(iam.get_role_inline_policy(RoleName=role_name, PolicyName=policy_name)['PolicyDocument'])
    response = iam.list_role_tags(RoleName=role_name)['Tags']
    
    # 然后删除 IAM 角色
    iam.delete_role(RoleName=role_name)
    print('Deleted IAM Role:', role_name)
    
    # 最后，删除角色之前策略、访问密钥和用户所依附的实体
    for entity in attached_entities:
        if entity['PolicyType'] == 'AWSManagedPolicy':
            iam.detach_role_policy(RoleName=role_name, PolicyArn=entity['PolicyArn