Sorry to pile on, but your question makes no sense.
1. If you e-filed a tax return, it can't be canceled. If it is accepted by the IRS, it will be processed. If it is incorrect, you will have to file an amended return after the first return is processed. Sometimes a tax return is rejected by the IRS after e-filing, this usually happens within the first 48 hours and means that something on the tax return didn't pass the IRS top-level verification process. In that case, it is if it was never filed. You can make corrections and re-submit when ready.
2. You never make withholding adjustments on a tax return. Withholding is the system used by employers to have the correct amount of tax withheld from each paycheck. If you want to change your withholding, you have to talk directly to your employers.
