要撤销 EC2 服务关联角色的临时凭证，可以使用以下代码示例中的步骤：

1. 导入必要的 AWS SDK 模块和库：

import boto3

2. 创建 IAM 客户端：

iam_client = boto3.client('iam')

3. 获取 EC2 实例的 IAM 角色名称：

instance_id = 'your_instance_id'
response = iam_client.describe_iam_instance_profile_associations(
    Filters=[
        {
            'Name': 'instance-id',
            'Values': [instance_id]
        }
    ]
)
iam_role_name = response['IamInstanceProfileAssociations'][0]['IamInstanceProfile']['Arn'].split('/')[-1]

4. 撤销 IAM 角色的临时凭证：

response = iam_client.list_instance_profiles_for_role(
    RoleName=iam_role_name
)
instance_profile_name = response['InstanceProfiles'][0]['InstanceProfileName']

response = iam_client.delete_instance_profile(
    InstanceProfileName=instance_profile_name
)

完整的代码示例如下：

import boto3

iam_client = boto3.client('iam')

def revoke_instance_role_credentials(instance_id):
    response = iam_client.describe_iam_instance_profile_associations(
        Filters=[
            {
                'Name': 'instance-id',
                'Values': [instance_id]
            }
        ]
    )
    iam_role_name = response['IamInstanceProfileAssociations'][0]['IamInstanceProfile']['Arn'].split('/')[-1]

    response = iam_client.list_instance_profiles_for_role(
        RoleName=iam_role_name
    )
    instance_profile_name = response['InstanceProfiles'][0]['InstanceProfileName']

    response = iam_client.delete_instance_profile(
        InstanceProfileName=instance_profile_name
    )
    
    return

# 调用函数来撤销 EC2 实例的 IAM 角色的临时凭证
instance_id = 'your_instance_id'
revoke_instance_role_credentials(instance_id)

请确保替换代码示例中的 'your_instance_id' 为实际的 EC2 实例 ID。