How to remove a mandatory of Party Role - Contract administrator in Project Contract.

Summary:

Do you know how to remove a mandatory of Party Role - Contract administrator in Project Contract?

Now, when I try to remove Contract administorator (Contract>Parties>Supplier>Team) , it is appeared the following error message.

I set like the following.

-Manage Contract Party Roles

-Manage Contract Contract Roles

Please let me know.

Thanks,

Mayuko