Introduction
If your server is hosted on OVH Hosting, and you need to update your PTR record, this article will point you to their support documentation, as this is the most up to date resource with instructions for their infrastructure.
Procedure
To update your Reverse DNS record, you should review the instructions provided and maintained by OVH from their documentation:
OVH - How to configure Reverse DNS
Once completed, you can verify the PTR record has changed using this article:
Resources
Please see "How to setup PTR (rDNS) records on your cPanel & WHM server" for instructions for other providers.