You are not able to find any option to delete the party role type Partner Contact.
Reproducing the Issue
1. Go to Customers workcenter
2. Select Accounts view
3. Select any Account
4. Go to tab Account Team
5. Select Add
6. Select the drop down menu for Party Role
You don't want the party role Partner Contact to show up in drop down list.
The party role Party Contact gets deployed if partner management is scoped with scoping question scoping question Would you like to manage partners, such as resellers, in your system?" or if account management is scoped.
Because of compatibility reasons this can't be changed in a way that the role only gets deployed if partner management is scoped.
If you want to remove the party role Partner Contact in the Account Team Maintenance you can do so using the codelist restrict.
KBA , LOD-CRM-ACC , Account , How To