可以使用AtlasClient API中的deleteAtlasTypeDefs()方法来删除创建的实体类型。首先，使用AtlasClient API登录到Atlas实例，然后使用getTypeDefs()方法获取已发布的类型定义。使用getType("relationship")方法并检查它是否为非空值。如果不为空，则使用deleteAtlasTypeDefs()方法删除该类型定义。以下是示例代码：

AtlasClient client = new AtlasClient(new String[]{atlasURL}, new String[]{userName, password});
List existingTypes = client.getTypeDefs(AtlasClient.DEFAULT_TYPE);
//get type with name "relationship"
AtlasType relationshipType = client.getType("relationship");
if(relationshipType != null){
     AtlasTypesDef typesToRemove = new AtlasTypesDef();
     typesToRemove.getEnumDefs().addAll(existingTypes.get(0).getEnumDefs());
     typesToRemove.getStructDefs().addAll(existingTypes.get(0).getStructDefs());
     typesToRemove.getClassificationDefs().addAll(existingTypes.get(0).getClassificationDefs());
     typesToRemove.getEntityDefs().add(relationshipType.getTypeDef());
     client.deleteAtlasTypeDefs(typesToRemove);
}