Prevent workers and managers from editing the qualifications in a performance document

Summary:

Our performance documents have a section where the worker and the manager evaluate the worker's performance against five qualifications (values). However, we discovered that the worker can add new qualifications or delete the automatically populated ones while the document is with them.

Question: how can we take away the ability of the user to add/remove these?

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

25A

Code Snippet (add any code snippets that support your topic, if applicable):