If a workflow manager install has failed, it’s possible to receive the above error or similar errors when attempting to re-run the workflow manager configuration wizard. Before re-running the wizard, it may be necessary to clean up existing databases by ‘dropping’ them.
To do this, open SQL Management Studio and locate the SbGatewayDatabase. Right click on it and select tasks –> detach. Place a checkmark in the drop box and click OK to drop the database.
Navigate to your SQL data folder, typically: c:/Program Files –> Microsoft SQL server –> MSSQL11.SHAREPOINT –> MSSQL –> Data
Locate the MDB and LDF files (SbGatewayDatabase and SbGatewayDatabase_log) and delete them or rename them.
Open Workflow Manager and run as administrator.
Re-run the Workflow manager configuration wizard.