Allowing deletion of private chat threads is on the backlog.
Please check “Teams/Skype Consumer chat and calling interop” on the public roadmap at microsoft.com/microsoft-365/roadmap?filters.. for updates.Havenn Murray commented
I honestly see a lot of people sticking with Skype for Business until it's completely deprecated if the ability to chat with people on the consumer version of Skype from Teams and vice versa isn't added.
As we announced at Microsoft Ignite 2019 this morning, we are excited to confirm that Multi-window capabilities are coming to Microsoft Teams, and will start rolling out to the public ring early next year!
Alex & the Teams team