macOS releasing static instance

Hi all,
in my app i have created static instance of catalog object.
+(Catalog *)getCatalogObject
{
if(staticCatalogObj == nil)
{
staticCatalogObj = [[Catalog alloc]init];
staticCatalogObj.catalogDictionary = [[NSMutableDictionary alloc] init];
staticCatalogObj.itemsArray = [[NSMutableArray alloc]init];

}
return staticCatalogObj;
}
how to release this catalog object now.

also if any class has property then do we need to release them,or only if we release the instance is fine.for ex

@interface items : NSObject {
NSString *productID;
NSString *vendorID;
NSString *itemPrice;
NSString *itemName;
NSString *itemDescrioption;
NSString *smallImage;
NSString *bigImage;
NSInteger quantity;
}
@property(nonatomic)NSInteger quantity;
@property(nonatomic,copy)NSString *productID;
@property(nonatomic,copy)NSString *vendorID;
@property(nonatomic,copy)NSString *itemPrice;
@property(nonatomic,copy)NSString *itemName;
@property(nonatomic,copy)NSString *itemDescrioption;
@property(nonatomic,copy)NSString *smallImage;
@property(nonatomic,copy)NSString *bigImage;

items *itemObject = [[items alloc]init];
itemObject.productID = @"565";

then do i need to do
[itemObject.productID release];

i have not writen dealloc function for this class.