How to find/edit the source list in data validation in a macro sheet?

[wablev]

Hi, I need help ASAP. Please refer to the attachment. I have this macro file which has a drop-down list. Objective: To edit the list and add CAD model instead of RDM model?
I tried to check the source in data validation, I see the source is "=Model_Options_NEW". Where is this coming from?

When I checked the same in the Formulas tab- Name manager it says it refers to "=CALCS!$I$4:$I$6". I do not see this calcs sheet? if it is hidden how to unhide and edit it?

Hoping to resolve this soon. Thanks