cancel my unconfirmed transactions, bounty

[bcpokey]

HI guys,

Could someone help me to cancel my unconfirmed transactions?
I can pay like 0.05btc for the assistance.

ps
I used electrum wallet

[unholycactus]

One way to "cancel" a transaction is to stop broadcasting it and hope it doesn't confirm.
That takes time.

The other way would require you to hand the control of your keys to someone else (or you could double spend your coins to invalidate your first transaction yourself).

[HI-TEC99]

Why do you want to cancel your transaction? Did you accidentally send it somewhere you didn't want it to go, or is it just taking too long to confirm?

[bcpokey]

yes I sent money to participate in ICO. But now it is over 

[barnes13]

yes I sent money to participate in ICO. But now it is over 

Just contact the developer team in ICO you participating, just giving them the Tx Id

They will sent back the Bitcoin to you, What ICO you participating?

[pedrog]

You need to double spend your bitcoin, create a new transaction to an address you own.

Check here:

Attempting a Replace-By-Fee (RBF) double spend transaction

What is an RBF transaction

A Replace-By-Fee transaction is a transaction that is nearly identical to your stuck transaction but pays a higher transaction fee. Since the original transaction most likely does not use Opt-in RBF, the RBF transaction that we will be creating will be considered a double spend and marked as such. The transaction uses Full-RBF and thus may still take a little bit longer to confirm as it is technically a double spend.

The difference between the types of RBF transactions

Replace-By-Fee transactions have 3 different types, First-Seen-Safe(FSS) RBF, Full RBF, and Opt-in RBF. FSS RBF requires that the RBF transaction include the same outputs as the transaction it replaces and consumes the same inputs. Full RBF means that the transaction is simply a double spend of another transaction but pays a higher transaction fee than the one(s) it replaces. Opt-in RBF means that the RBF transaction can only replace a transaction that has Opted-in to allowing itself to be replaced. Opt-in RBF follows [urlhttps://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki]BIP 125[/url].

The instructions given in this section will be for making Full RBF transactions. Opt-in RBF transactions will be described in the "Avoiding Stuck Transactions In The Future" section.

How to make a Full RBF transaction

Making a Full RBF transaction depends entirely on the wallet that you are using. Some wallet support the advanced functionality required to make a Full RBF transaction, others do not. The following will be guides for each wallet on how to make a Full RBF transaction with that wallet. In general the procedure is to remove the unconfirmed transaction from the wallet and then resend the Bitcoin but with a higher transaction fee.

When making a Full RBF transaction, the transaction should include the recommended fee rate at the time of creating the transaction. See the "Avoiding this issue in the future" section for help with that.

Bitcoin Core

Bitcoin Core makes making Full RBF transactions very easy. Simply go to the transactions list, right click the transaction that is stuck, and choose the "Abandon Transaction" option.

If that option is greyed out, then you must restart Bitcoin Core with the -walletbroadcast=0 option and then you should be able to use "Abandon Transaction".

If the above two options fail for some reason, then you can start Bitcoin Core with the -zapwallettxes option to clear all unconfirmed transactions from your wallet.

Once the transaction is either Abandoned or cleared from the wallet, you can simply go to the Send tab and send the Bitcoin again but make sure that you include a sufficient transaction fee.

Bitcoin Armory

Bitcoin Armory also makes making Full RBF transactions very easy. Go to Help > Clear All Unconfirmed Transactions and restart Armory. This will clear all of the unconfirmed transactions from the wallet and thus allow you to create the Full RBF transaction. Once Armory has restarted, simply send the Bitcoin again as you normally would but be sure to include a sufficient transaction fee.

MultiBit HD

MultiBit HD allows for making Full RBF transactions fairly easy as well. Go to Manage Wallet and click on Repair Wallet and follow the wizard. This process will clear all of the unconfirmed transactions from your wallet much like Bitcoin Core and Armory do. Once repair wallet has completed, simply send the Bitcoin again as you normally would.

Wallets that do not allow you to or ones that I don't know how to make Full RBF transactions

Not all wallets support the creation of Full RBF transactions. Many wallets do not allow clearing all unconfirmed transactions to allow for making Full RBF transactions. The following is a list of wallet software which do not support Full RBF transactions. If a wallet on this list does support FullRBF transactions, please let me know and provide instructions for that so I can add it above.

• Blockchain.info and web wallets in general
• Electrum (supports Opt-in RBF, but not Full RBF)
• Mycelium
• MultiBit Classic
• Bitcoin Wallet for Android
• Breadwallet
• Copay

[carlfebz2]

yes I sent money to participate in ICO. But now it is over 

Just contact the developer team in ICO you participating, just giving them the Tx Id

They will sent back the Bitcoin to you, What ICO you participating?

This is only the best possible solution as of now because we do know btc transactions cant be reversed and theres only one way on where those bitcoins will go but only to the Developer teams wallet of a particular ICO. I think no one could able to help you regarding on this matter but only yourself. Just tell them that they should send it back since the ICO is already over.