YOU CANNOT.
Here's the thing, what GCash/Globe keeps is your PayPal account email. Any transaction you do in GCash will be forwarded to PayPal and you will still do whatever authorization steps PayPal requires. There is no real "link" between GCash and PayPal.
UNFORTUNATELY, you cannot "unlink" or delete the PayPal account email they have stored in your GCash. Globe/GCash don't allow it. If you really wanted a GCash account with that information not stored, you would have to CREATE A NEW GCASH ACCCOUNT (and delete the old one).
