You can delete categories one at a time using the Categories screen (the same screen you use to add categories to Inventory Control).
You can also use the Delete Inactive Records screen in the I/C Periodic Processing folder to delete groups of categories.
Note: You cannot delete a category if any item records are assigned to it. You must first assign its item records to another category or delete them.
Setting Categories Inactive before Deletion
Before trying to delete a category, you can set the category record Inactive to ensure that no additional items are assigned to it.
You can then wait until the end of the fiscal or calendar year to delete it (depending on the method you use to accumulate item statistics).
You use the I/C Categories screen to make categories inactive.
Identifying Inactive Categories
Print the Categories report to identify inactive categories. If a category is inactive, the date it was made inactive appears on this report in the Inactive On field.