Yes....that is possible but through customization. We achived it for 8.1.
Steps:1. Insert ShowInteractionsWindow in chain of command.
2. Unde Execute find InteractionsWindow from parameters to get current ixn window reference.
3. Find 'TabItem' control named 'Genesyslab.Desktop.Modules.Windows.Interactions.CaseHeaderView' in current ixn window.
4. Once you have reference of this TabItem, you can disable it now.
Regards,
Rohit Gupta