The ERwin UI currently only allows for UDP deletion on a one by one basis. This is not practical for people who have tens if not hundreds of UDPs they want deleted from a model.
The attached Excel workbook uses the ERwin API to list the UDPs found in a model (using eMovies as an example):
You can then delete the rows containing the UDPs you want to keep thereby leaving those UDPs you want to delete from the model.
The workbook will prompt you to make a backup (on your behalf) prior to deleting the UDPs but it is always better to make one manually prior to making changes to models using the API.
Although this has been tested quite thoroughly you are advised to use it your own risk!