A Records are a part of the DNS system and are used to route web traffic to a particular server.
You can usually edit your A records by logging into your Domain Control Panel with your domain registrar and locating the “Manage DNS”, “Edit DNS” or “DNS Zones” Settings.
Your web hosting welcome email will advise which settings to use here.
You should delete any old settings but we advise making a record of these before deleting to aid recovery in the event of any issues.