Utilícelo AbortMultipartUploads con un o AWS SDK CLI

    using System;
    using System.Threading.Tasks;
    using Amazon.S3;
    using Amazon.S3.Transfer;

    /// <summary>
    /// This example shows how to use the Amazon Simple Storage Service
    /// (Amazon S3) to stop a multi-part upload process using the Amazon S3
    /// TransferUtility.
    /// </summary>
    public class AbortMPU
    {
        public static async Task Main()
        {
            string bucketName = "doc-example-bucket";

            // If the AWS Region defined for your default user is different
            // from the Region where your Amazon S3 bucket is located,
            // pass the Region name to the S3 client object's constructor.
            // For example: RegionEndpoint.USWest2.
            IAmazonS3 client = new AmazonS3Client();

            await AbortMPUAsync(client, bucketName);
        }

        /// <summary>
        /// Cancels the multi-part copy process.
        /// </summary>
        /// <param name="client">The initialized client object used to create
        /// the TransferUtility object.</param>
        /// <param name="bucketName">The name of the S3 bucket where the
        /// multi-part copy operation is in progress.</param>
        public static async Task AbortMPUAsync(IAmazonS3 client, string bucketName)
        {
            try
            {
                var transferUtility = new TransferUtility(client);

                // Cancel all in-progress uploads initiated before the specified date.
                await transferUtility.AbortMultipartUploadsAsync(
                    bucketName, DateTime.Now.AddDays(-7));
            }
            catch (AmazonS3Exception e)
            {
                Console.WriteLine($"Error: {e.Message}");
            }
        }
    }