As long as you have a role with permissions in the course (Teacher, Ta, etc.) that allows you to delete discussion posts, then yes, you can delete the post. That is the technical answer. 

As far as it being confusing to other students, as a teacher, I would reach out to that student before deleting and ask for clarification in their post. What were the intentions or message they are trying to convey? Did they post to the wrong location? Etc. Depending on the response, I would consider deleting the post or asking them to resubmit the discussion. Or if it is a graded assignment, I would grade the post as-is. But I would talk to the student first and base my action on what they have to say.