Of course that didn't work because you don't place an identifier without an executing command to trigger it, unless you call it from an alias.
This is what you should have done:
scid 1 msg #updates $remove($1-,|)
If you choose to use $replace, you don't need an extra $1- at the end.
scid 1 msg #updates $replace($1-,|,||)
will be enough, or you can replace || with $chr(32) aka a space.
Finally though you don't need // at all.