Removes existing files associated with an item.
NOTE: This function will not alter facets which can also
contain facets. To manipulate facets, the facet element of
a sciencebase item must be altered and updated with item_update
.
This function is the key way to remove files attached to SB items.
Examples
if (FALSE) {
res <- item_create(user_id(), "item456")
cat("foo bar", file = "foobar.txt")
item_append_files(res, "foobar.txt")
res <- item_get(res)
res$files[[1]]$name
res2 <- item_rm_files(res)
res2$files
}