You've just imported a run of 20 plates, and realize one of the plates was not prepared correctly. You need to delete the run data for this plate, and re-run it. Since the rest of the run is fine, you don't want to delete the entire run.
- Go to Explore Data tab-> Protocols sub-tab -> click Protocol Name -> click Run Date -> Data Summary sub-tab.
- Click the delete link found to the left of the plate name. All the data for this plate that you imported into this run is now deleted. There is no need to delete the original import file, and the compound plate map is still in the vault, so there is no need to reimport it.