You can not do that in QB.
An assembly item build does not allow for waste or drops. The assembly item uses the complete item in the BOM
Resolution for 'complete item issue: 'How to find out the materials left in department?' available: Yes.
The complete item issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the complete item issue yourself by looking for a resolution described in the article. If it is a complex complete item issue or you are unable to solve the issue, you may contact us by clicking here or by using other complete item support options.
For more information about resolving issues related to complete item in Quickbooks/QBO or to get support for the issue 'How to find out the materials left in department?', click the link below: