An alternate way to remove the user other than using the WebUI.
You may run the CLI command below to remove the user.
echo "delete from users where username='<Username>'" | su - postgres -c "psql -d dsweb"
For example, if you are trying to delete the user 'helpdesk1', you would run the following command:
echo "delete from users where username='helpdesk1'" | su - postgres -c "psql -d dsweb"