Limiting Individual Compensation elements in Recruitment and New Person Workflows

We currently have a number of compensation plans configured in Individual Compensation Plans which we use in recruitment and new person HCM workflows to assign allowances. After 5 years we now need to reduce the available options that appear from 9 to just 1 plan.

A few questions on the best way to do this:

• How can we remove the unwanted options from the list of option in the compensation block of HCM workflows, without impact elements that are already assigned to employees (i.e. they should still be paid these)? The requirement is to hide the options for future allocation via HCM workflows without impact those already in use. We would also need the elements available to assign in the backend still via Element Entries.