That's a moot point.

Meaning

That point is irrelevant or no longer important.

Examples

• John: I think we should reconsider our previous decision.
• Alice: I don't agree; <b>that's a moot point</b>. The deadline has already passed.
• John: But perhaps we can adjust the next deadline.
• Alice: Unfortunately, <b>that's a moot point</b>; we have already signed a contract.