Step 1:
First , You need to log into your PayPal Account .
Step 2:
Click your account name, and then select Account Settings.
Step 3:
Under the API Access heading, click Update.
Step 4:
And then , Under the Pre-built Payment Solutions heading, click Manage API permission.

Step 5:
Then , Click on clickbank checkbox .

Step 6:
On the Are you sure? screen, click Yes, revoke.
Tip: When you deselect the PayPal check box, your PayPal account is no longer connected to your ClickBank account.
NOTE: PayPal is a registered trademark of PayPal, Inc. The PayPal logo is a trademark of PayPal, Inc.