Stop bitcoin-qt from retrying transaction
Yes, Bitcoin Core will try resending the transaction until it confirms or is replaced. You can make it forget the transaction by starting Bitcoin Core with the option

-zapwallettxes=&lt;mode&gt;

Then, be sure to use the inputs in another transaction, because the transaction is still valid and might yet be confirmed. The only way to invalidate it is by doublespending the coins.

The easiest way to make sure that you have invalidated the old transaction is by moving your wallet's complete balance to a new address.