Just drag the photos from smart collection into a regular collection. first you have to create the regular collection, then you have to delete the smart collection - there is no one-key conversion that I am aware of.
If you want to convert a smart collection to a folder-folder (disk-folder I mean, as opposed to a true collection), then right-click (ctrl-click on Mac) the parent folder, and create a new folder - opt to include selected photos. (delete smart collection afterward)
Me? I use smart collections for almost everything collection-wise, except to-do collections, since photos disappear from a smart collection once the to-do criteria is cleared, which is sometimes too soon.
To each their own..
WAIT - hold the press.. - if your problem is just the name of the smart "folder" (collection), then yeah - just rename it. I mean, if it's a publish collection then your service may disallow renaming, but otherwise, just right/ctrl-click and choose to rename - no?