First of all - you need open Anycast Dns service by click to "Anycast Dns" service in our billing system
After that - choose domain name for which you want change/add/remove domain text record and click to choosed domain, in my case - it's domain "qwe123.com" :
To edit or delete any entry, click the "Edit & Delete" button next to the entry you want to edit/delete :
To add new records, select the record you want to add and click on " add". In my case - i'll add TXT record
The last step, enter the data of the record that you want to use and click on the button "submit" :