If you want to clean out larger portions of your data, the Excel Import is an easy approach.
Your Excel file contains all segments like you see them in your account:
The Excel Import handles every segment individually when importing. You may import Applications for products A, B, and C in the same file as the PartAttributes for products D, E, and F.
When importing data, the data in your import file will overwrite the data in your account after comparing the data from the Excel sheet to the data in the database. Missing values in Excel are considered to be deleted. Looking at the example above, only the Applications of the products A, B, and C would be updated. For the products D, E, and F only the Attributes will be updated.
If you want to delete all applications of certain products, simply import those part numbers with just the part number and brandID. Existing applications will be updated to "nothing".
Remember that all data points of the segment you are importing first gets compared and updated/deleted. Example: If you want to change retail pricing you have to export all prices (including WD, jobber etc.), then change the retail price and reimport the retail price along with the WD and jobber prices). Importing only the retail price will be considered that the other prices (WD, jobber etc.) should get deleted.