I'll go ahead and lock it up.
If you ever want to lock/delete/hide one of your threads in the future, I think you can do the the following:
In the upper right corner of your original post there's three horizontal dots that, when you click, should give you a dropdown.
That dropdown should at least have an edit option you can click on that should provide several boxes to choose from; the dropdown itself may also even contain those other options in addition to the edit button. I can't be 100% certain what the user layout looks like compared to the mod layout.