Actually, you could use an Azure Function ("TimeTrigger" type) to periodically purge your tables, here is an example of code to use inside a C# TimeTrigger Azure Function to get a connexion to your Azure Sql Database and execute "delete" sql queries :
#r "System.Data"
using System;
using System.Data.SqlClient;
public static async Task Run(TimerInfo myTimer, TraceWriter log)
{
    string userName = "*******";
    string passWord = "********";
    var connectionString = $"Server=tcp:work-on-  sqlazure.database.windows.net,1433;Data Source=work-on-sqlazure.database.windows.net;Initial Catalog=VideoStore;Persist Security Info=False;User ID={userName};Password={passWord};Pooling=False;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;";
    using(SqlConnection cns = new SqlConnection(connectionString))
    {
         cns.Open();
         var truncateUserTable = "DELETE FROM Video";
         using(SqlCommand cmd = new SqlCommand(truncateUserTable, cns))
         {
             int rowsDeleted = await cmd.ExecuteNonQueryAsync();
         }
    }
}
Then you can configure the timer logic from the Azure Azure Function "integrate" space with a cron expression.