Thank you for reaching out!
At this time there is not a way to remove or filter out branches from the pipeline view. We actually do have an open feature request that is similar to what you’re requesting that can be found here: Ability to "Hide" old branches from UI | Cloud Feature Requests | CircleCI Ideas
I encourage you to check this out, add an upvote, and a comment with some clarification around how you would like to see this feature work.
In the meantime, the best way to remove the clutter would be to have this cron job run on its own branch and then view individual branches rather than all branches at the same time. While this may limit some visibility, it should also provide clarity on the branches you need.
I hope this helps, and please feel free to let us know if you have additional questions!