SF_10.1, SF_10.2, SF_11.0, SF_11.1, SF_11.2, SF_12.0, SF_12.1, SF_12.2, SF_13.0, SF_13.1, SF_13.2, SF_13.3, SF_14.0, SF_14.1, SF_14.2, SF_14.3 - https://docs.sitefinity.com/for-developers-change-the-url-format-of-hierarchical-dynamic-modules

RemoveParentFromChildURLAllTypes.cs

using System;
using Telerik.Sitefinity.DynamicModules.Model;

namespace SitefinityWebApp
{
    public class RemoveParentFromChildURLAllTypes : Telerik.Sitefinity.DynamicModules.Data.OpenAccessDynamicModuleProvider
    {
        private bool resolvingChildUrlFormat = false;

        /// <inheritdoc />
        public override string GetUrlFormat(Telerik.Sitefinity.GenericContent.Model.ILocatable item)
        {
            string urlFormat = "/[UrlName]";
            var resolvedItem = (DynamicContent)item;
            if (!this.resolvingChildUrlFormat && resolvedItem.SystemParentId != Guid.Empty)
            {
                this.resolvingChildUrlFormat = true;
            }
            else if (this.resolvingChildUrlFormat)
            {
                urlFormat = string.Empty;
                if (resolvedItem.SystemParentId == Guid.Empty)
                {
                    // Stop child url format resolving when we reach the topmost parent
                    this.resolvingChildUrlFormat = false;
                }
            }

            return urlFormat;
        }
    }
}