Can someone withdraw a Notice of Objection to a will after filing it in Ontario?

Yes. A person who filed a Notice of Objection can withdraw it, and often does once they've had a chance to review the will file, get disclosure, or reconsider the strength of their concern. Withdrawal is generally straightforward: the person who filed it notifies the court and the other interested parties that they no longer object, which clears the way for the probate application to proceed once the withdrawal is on the record.

Withdrawing doesn't necessarily end the matter of costs. If the objection caused the estate to incur legal fees defending the will, or delayed the estate significantly, the estate trustee can ask the court to order the person who withdrew to pay some or all of those costs, particularly if the objection appears to have been filed without a reasonable basis. Courts have discretion here and consider the circumstances, including whether the objection was withdrawn promptly once new information came to light or only after significant expense had already been incurred. Anyone thinking about withdrawing an objection should get advice on how withdrawal might affect their exposure to costs, rather than assuming that walking away ends their involvement in the matter entirely.