First of all, I don't know how to close this issue. because i am new here. If someone explains how to turn it off, I'll turn it off.
Depends on how you want to proceed. You can lock the topic so that no one can post new replies anymore, as @yahoo suggested. Or you can move the topic to "Other - Archival" so no one will be able to see it here anymore.
Both options, "Move Topic" and "Lock topic", are located in the lower left corner of this page.