Remove the unneeded users from that approval.
Unfortunately there's no true way to withdraw an approval at this stage. What you can do instead is remove users from an approval and replace them with dummy users instead. Head to your approval details and edit your approvers.
When you Edit Approvers, admation will prompt you to add at least one approver to each level or group. There is no way to get around this message.
Please add the admation support email under the external users tab, (or even your own email) to this list. If adding dummy approvers to approvals isn't quite your thing, we completely get it! In that case, you can contact admation support to action this work around for you instead. Otherwise, once you've filled all levels and groups with a "dummy approver", click Done.
Admation will prompt you to send an email to the people you've removed from the approval, to let them know that their approval is no longer required. Then click Continue to confirm your changes.