On the Websites and Marketing builder you cannot. GoDaddy writes and serves that file and it is not exposed to you in any setting. Saying so plainly is more use than sending you round the settings looking for a screen that does not exist.
If your site is WordPress hosted at GoDaddy rather than built in their site builder, none of this applies and the WordPress guide is the one you want.
Find out whether it is actually the problem
Open
yourdomain.com/robots.txtand read it. If none of the four answer crawlers is named with a blanket disallow, the file is not what is blocking you.Read the technical detail on the finding. It distinguishes a crawler refused by robots.txt from one turned away by a firewall. The second is far more common here.
If it is a firewall, check anything you put in front of the site yourself. If you did not put anything there, it is GoDaddy’s infrastructure and their support is the only route.
What this costs you
Crawler access carries the heaviest weight in the scan, so being unable to change it on a platform that has blocked you is the worst position on this list to be in. It is also, in practice, uncommon: most GoDaddy sites pass this check without anybody doing anything.
If yours does not, and support will not move, that is worth knowing when you next decide what to build on. It is the one finding where the platform itself is the answer.
If your screens do not look like this, the wording has moved rather than the setting. Search your platform for the words in bold above. If you still cannot find it, send us the scan link and we will tell you where it is on your setup.