To change your Payoneer account with AdFly is a 2 stage process.
1. Go to:
and click the link to remove your Payoneer account. This link is only available if currently you have an 'active' account.
2. Contact Payoneer:
and ask them to remove the association between your AdFly account ID (the number in your referral link) and your Payoneer account.
When this has been done, you can then revisit:
and click the register link. Here you will be able to either create a new Payoneer account or login to an existing one.