Are these red cylinder things supposed to come off before use? I would think so, but they don’t come off easily…
Not usually. It doesn’t really matter either way unless you are cutting really deep.
The ones I’ve seen have a size stamped on them to identify what size they are. I’ve never removed them. Normally just insert and start.
I remove them from tools I’m doing serious cutting with so I can choke up on the tool as much as ideal for whatever stock. On lighter duty tools I mostly leave them on.
They have a use, but can come off.