is it possible in some other way?
I'm afraid you're gonna have to either delete some stuff to make room, either use a web wallet (it takes care of keeping a copy of the blockchain synced for you).
If anything, you can always buy a cheap USB key and tell the wallet to store the blockchain on it.
thanks for your help. How can i use a web wallet? I've heard about coinomi. Can i use it? what i have to do?
Don't know about coinomi but bear in mind that any exchange that supports BTG is pretty much always offering a BTG web wallet.
So Bittrex, Cryptopia... any exchange that offers BTG trading can be used as a web wallet for BTG (restrictions may apply, such as mining directly to the wallet and whatnot).