我刚好去ovh客服那里问了
If you would like for the VPS to cancel at its expiration date please do the following steps:
1. Login to your OVH Control Panel.
2. Click on Billing on top of page.
3. Click on My Services on left side of page.
4. Beside the VPS in question click on the cog and click Terminate Service.
If you would like to terminate the server immediately, please do the following steps.
1. Go to https://ca.api.ovh.com/console/#/vps/%7BserviceName%7D/terminate#POST
2. Login at top of the page with your OVH credentials
3. Input your service name in the field: e.g. vps123456.vps.ovh.ca
4. Click execute
5. Find the confirmation e-mail and click the confirmation link.