Once a remediation plan is Activated it is Sent for approval and an Issue is opened in ServiceNow requiring your attention under Change > Open. The ticket Approval status is by default 'Requested'
In order to Approve the ticket: double click the approval status and select 'Approved'. Once the ticket is approved, the remediation plan will move to 'In Progress'.
If you would like to reject the ticket (and decline the remediation plan) double click the status and select 'Rejected'. If the ticket is indeed rejected, the remediation plan will be canceled with status 'Rejected'.