If the transfer was made more than 1 business day ago, it is not possible to cancel the payment, as it has already been forwarded to the recipient/beneficiary organization. You will need to contact them to have the amount refunded to you.
A wire transfer can be cancelled on the business day it was made or the next day until 09:30 a.m. or 01:00 p.m. depending on the time it was made.