https://userapps.support.sap.com/sap/support/knowledge/en/1933405
1933405 - "Drop disallowed for dbspace" error - SAP IQ | SAP Knowledge Base Article
A customer encountered below error when tried to drop a db file. In normal situation, DB file can be dropped when the db file is empty. In spite the db file...
sap iqknowledge basedropdisallowed