If you are using Cloudflare nameservers, you manage your DNS A records at Cloudflare.
1. Login to your Cloudflare dashboard and click on the domain name you want update
2. Click the DNS button from the top menu:
3. Locate your domain’s A record (under the Type column), and click the Edit button on the right
4. Delete the old IP address and replace it with the new IP address under the IPv4 Address field, and click the Save button
It can take up to 24 hours for the DNS changes to load across the internet. DNS propagation is the process of updating every server across the internet with new information globally.