I need to create a formula that locks opportunities once they reach a certain stage. We want only a the administrator to be able to make changes once the opportunity hits the stage so we can make sure the date and the amounts don't change. Can someone help explain how I would go about creating the formula or if this is even possible?

I need to create a formula that locks opportunities once they reach a certain stage. We want only a the administrator to be able to make changes once the opportunity hits the stage so we can make sure the date and the amounts don't change. Can someone help explain how I would go about creating the formula or if this is even possible?

Hi....I need a Validation rule that says once a certain custom Check Box field has been ticked, the Opportunity is no longer editable. Check Box will only be accessible by System Admin.  Reason is we will be driving certain other process from a finalised Opportunity and can't have any of the details changed once it is being used in the other processes....thanks