In form template settings for a given Performance Management form, there is the option to select "Disable Note button".
When selected, the expectation is to not display Notes within the supporting pod information of a launched PM form. However, the Notes are still available.
SAP SuccessFactors Performance Management
The setting 'Disable Note Button' works for PMV11 based forms, as Multi-Rater forms, not 'Performance Management V12 Acceleration'.
The Disable Note Button is not supported for PMV12A forms, the alternative in this case would be to Remove the permission to the Supporting Pod as there is no other feature to hide only the Notes within the form.
In case you would like to see the desired functionality implemented in a future release of the product, we strongly suggest you to post your idea on the Influence Portal, the steps to do so are related in the KBA 2090228 - How to Submit Ideas for SAP SuccessFactors Products.
Disable Notes Button, Notes in performance form, supporting pod information , KBA , LOD-SF-PM-ADM , Admin Center, RBP, Permissions and Settings , Problem