You probably want your customers and support agents to access your support portal in your own vanity URL. You can point your support URL at yourcompany.freshdesk.com to your own domain, like support.mycompany.com. Just make sure you have created a CNAME record in your DNS zone file to point your vanity URL to your Freshdesk domain.
Quick guide to setting up Freshdesk on your own URL
Step 1: Creating a CNAME record in your DNS Zone File
Login to your Domain Control Panel
Go to the section which says DNS or Name Servers.
Create a new DNS record and point your custom support URL to demo.freshdesk.com. You may need to fill in these details:
Alias Name: Enter the subdomain name for your alias. For example, if you want to use a vanity support URL like support.mycompany.com, enter "support" as your alias name
Point to Host Name: Type @ to directly map the alias to your domain
TTL: Enter a Time To Live between 30 minutes to 1 hour, or leave this field in its default settings
Save changes to your DNS records.
Note that these instructions may vary a bit based on your domain registrar. If you are unable to find a way to add the DNS record, get help from your webmaster or your server administrator.
Step 2: Setting up your Helpdesk URL in Freshdesk
After creating the CNAME record, login to your Freshdesk portal
Go to Admin-->Helpdesk Rebranding
Learn more about Rebranding your Freshdesk Account here.
Under Helpdesk URL type your vanity support URL (support.mycompany.com)
Click Save to save the new settings
Once done, you can verify your changes by entering your support URL in this page and looking up your CNAME records.