pipeline, can I control the tags that the tasks a pipeline creates? 

add_pipeline_tags

  adds tags from pipeline to the tasks I suppose? But I also need to clear existing tags in those created tasks

add_pipeline_tags will add the unique ID of the pipeline execution, if you want to add specific tags you can use the task_overrides and provide:
pipe.add_step(..., task_overrides={'tags': ['my', 'tags']})