Hi Todd Raymond1,
Greetings. Thank you for posting the thread to our community.
Based on your description, it seems you want to delete unused Labels in Planner for Teams
As far as I know, after researched and gathered all the information I’m afraid and sorry to say currently it is not available to delete unused Labels in Planner for Teams. For this limitation you’ve encountered, I do understand the inconvenience and sorry about it.
It definitely great improvement to the current availabilities of Microsoft 365 apps. In that case, I sincerely recommend you go to Feedback community to vote this similar feedback: (find out similar feedback, if not provide the feedback forum link Ideas · Community). Our product team is in charge of the site, and they constantly check customer reviews and feedback, The higher votes, the more attention the related team will pay on. And a lot of features are developed and improved based on customer feedback.
Please notice and accept my apologies that as moderators in the community, we are not supported for the product design and have limited resources for the advanced info for Microsoft products. To help you send your feedback and requirement to the related development team, we have redirected you to the correct path.
Thanks you and Have a good day.
Best regards.
Sting-Ng - Microsoft Community Support Specialist.