Java 8 从List中移除一个元素

Question

I am trying to remove an element from a list which has a nested list. Below is my class

   class Pets
   private Long id;
   private String categoryName;
  private List<PetCategory> petCategory;
 //setter & getter

   public class PetCategory {
   private String PetCategoryName;
   private String petSymbol;
   private List<PetList> petList;
 //setter & getter
   }

  public class PetList {

  private String petName;
  private String petWithPicture;
  private List<PetAnimalType> petanimaltype;
 //setter & getter
}

public class PetAnimalType {
private String PetAnimalTypeName;
private String PetAnimalId;
private List<String> petbreeds;

I am trying to remove an element from List by passing the PetAnimalTypeName. I am getting this PetAnimalTypeName as a list

 List<String> checkPetAnimalTypeName=new ArrayList<String>();
 checkPetAnimalTypeName.add("test1");
 checkPetAnimalTypeName.add("test2");

    for(String s1:checkPetAnimalTypeName) {

             m.getpetCategory().stream().filter(x ->
             x.getPetCategoryName().equalsIgnoreCase("somename")) .flatMap(y ->
             y.getPetList().stream()).filter(s ->
              s.getPetName().equalsIgnoreCase("somename")).

             forEach(v->v.getPetanimaltype().removeIf(x1->x1.getPetAnimalTypeName()==s1));

              }

It is not removing the element from the List. Could you please help me how to remove the element and better way of echieving this logic