Hello,
You probably know that, but you should never have bought any btc.
That said, you can send them whenever you want. A btc address is basically 2 keys: public key and private key. public key for receiving coins, and private key for sending them.
You can create a paper wallet here:
https://www.bitaddress.org (or somewhere else). Just send your btc in the public address, and keep the private address to use them when you need to.
Blockchain or coinbase are not safe: if you don't own (and only you) the private key, you don't really own the bitcoins.