A key characteristic of bitcoin is that once a transaction is valid, it remains valid and does not expire. Upon a transaction happens, with little risk, that the transaction will shortly be included in a block and confirmed.
But there is a way to cancel a transaction by double-spending its inputs with another transaction before it is mined. Also by connecting the wallet into your desired network as earlier discussed at here you can do it much more easier !
You can study more about bitcoin vulnerabilities here: