If you have inactivated customer or vendors, GP allow you to hide them from the Default lookup screen:

BEFORE:

    1. Make sure the Vendor/Customer is marked as “Inactive”
    2. Click the Drop-Down by the word “View”

  1. Choose “Exclude Inactive Customers”
  2. Click the Drop-Down again
  3. Choose “Set as Default View”
Note: This is setup by user/by screen