The unique characteristic of blockchain and cryptocurrency technology is that once a transaction is sent to the blockchain network, it cannot be cancelled or modified.
Therefore, the only option for users is to wait for a pending transaction to complete. If a pending transaction remains unverified by the blockchain network for an extended period, it will eventually be cancelled.
However, there's an exceptional case for Ethereum transactions.
You might be able to cancel a pending Ethereum transaction by sending a small amount of Ethereum to your own address with a significantly higher gas price. Since the newly submitted transaction (with higher gas) gets processed first, it will effectively cancel the original pending transaction.