Unable to delete sequence in Postgresql

I have some trouble with DeleteNumber (domain) I have created a sequence Demo in lowerletters. When I try to delete it I get an error. Demo not found. I am using Postgresql.

If I try to remove seq_un_demo sequence in Postgresql. I get an error telling me that seq_un_demo is not found when I try to create it in Cuba-platform again. Is there any table I can’t see in Postgresql? Where is sequence entries saved in Cuba-platform?

Some how I manage to fix it.