You can’t change a Cloudflare Registrar domain’s nameservers yourself… that’s why you don’t see an option in the dashboard to do this.
Did you remove the site from Cloudflare prior to this? If so, then you’d be assigned a new pair of nameservers when you add the domain back. If this is the case, then you need to open a support ticket for the Cloudflare support team to fix this.
If you’re absolutely sure you never deleted the site, then you’re in a Cloudflare account that is different from the account where the domain was registered. You need to log out of the current account and login to the correct account to use the domain. If you can’t remember what the correct account is, enter the domain here to find out: https://dash.cloudflare.com/forgot-email
Oh, sorry I didn’t look up the domain itself before replying
While everything I said above is true, in your case the domain avantechit.com expired a long time ago (February 10, 2025) and entered into redemptionPeriod just today, 22nd March.
You can’t use or even simply renew a domain that already has redemptionPeriod status. Neither can you transfer a domain in this state. You may not even see the domain in your Cloudflare Registrar dashboard at all (under “Manage Domains”).
You need to open a Registrar support ticket to have the domain restored. Note that there will be a restoration/redemption fee on top of the usual renewal fee. This restoration fee is charged by the registry operator and Cloudflare cannot waive it. See my recent post on this subject here: I can’t access Manage Domain to renew expired domain - #14 by GeorgeAppiah
Finally, note that domains remain in redemptionPeriod for 30 days. Following this, they go into pendingDelete for a further 5 days… after which they’re completely released for anyone to register. See: FAQ · Cloudflare Registrar docs
That means if you absolutely want your domain, you should take action and pay any necessary fees to restore it immediately. You cannot restore a domain once it enters pendingDelete state, and there’s –NO– guarantee that you can “catch” it once it drops: there’s a whole industry of people who use sophisticated tools to catch (what they consider) valuable domains the second they’re released.
First, check to see if the domain is in your dashboard under Domain Registration → Manage Domains, and if there’s any action you can take yourself to restore the domain.