renaming a system object

hi all,

i have a user table that has been promoted to a system table a while back.  In the property, I see that the table System Object = True.

I tried looking for a way to revert this table back to a normal table but unable to ID any article.  So I went and copy the data from this table to another but when I tried to rename the old table via sp_rename, I get a msg that state SSMS can't find the table i'm trying to rename.

Any suggestions on how to do this or better yet, how to revert my user table back to a regular table?!

Thanks