You won't be able to control this in the list itself (i.e. if the user opens the list, and puts it in quick edit mode or something). But in the form, you can check if the Supply Chain Approver accountid field is not equal to the username function. For the conditional formatting on the status field, in the first dropdown, find the group for the Supply Chain Approver (you will have to put the data source in advanced mode) and select the account id field inside it. For the second dropdown, select "is not equal to". For the third dropdown, use a formula or group, and in the functions, select the user name function. Then you can select formatting to disable the control.
Hilary Stoupa
