Depending on the situation, you can't actually do it via SQL or in bulk. The warnings themselves would need to be expired/deleted via the relevant user's profile page. (The users with warnings could be identified based on the user_id values in the xf_warning table.)
You should be able bulk update xf_warning.expired_date for all non-expired jobs and then run the cron task to allow all XenForo to expire the warnings.
You do not need an add-on to remove warning link under posts (as that seems it is all the add-on does.). Revoke the necessary permission to warn posts and it will disappear.
You should be able bulk update xf_warning.expired_date for all non-expired jobs and then run the cron task to allow all XenForo to expire the warnings.
That is better thanks for pointing that out. One more question if I may. Does expired points mean threshold will start from scratch? or will it consider points already given even if its expired? or threshold action only applies to non-expired points? XF warning system is a bit confusing.