Why can't I delete custom countries?
Could you link to the mod you are having an issue with, along with a country which isn't deleting?
https://edge.hoi4modding.com/mod/10972
ALL OF THEM
This is because you are not the original owner of the mod.
To stop team members from potentially deleting all countries from the mod, only administators* can delete anything within the mod (focus trees, start dates, countries, etc.)
*Administrators being site admins (currently just me) and the person who has created the mod originally - in your case @TheLuckyPookie
I will possibly add a way in the future to add someone else as an administrator, but that won't be for at least a few weeks.
Andrix
I deleted them all multiple times but they just keep reappearing.
I changed the ideologies after the countries have been created but isn't there a way to fix this?
I definitely want to see that fix in the next update to this site.