To generalise this question, the offending entry exists in the res.partner.bank model. There seems to be no user interface for this model, so the proffered "Archive it if possible" is not an option without resorting to custom coding (at least in Odoo 14, but I don't think it changed since).

The problem frequently pops up with payments (either inbound or outbound) through clearing houses such as Mollie, Stripe or Tikkie. When a clearing house bank account gets associated with a specific supplier or customer, there appears to be no way to undo that.

If ever I come up with a proper solution, even if it's only achievable through scripting, I'll post it here. So far a solution has escaped me.