How do I disable both the Competitors and Reason Won/Lost required fields and when closing my opportunity?

The Close Opportunity Win/Loss Reason Required profile option (MOO_CLOSE_WINLOSS_REQD) lets you specify whether salespeople must enter a win/loss reason when closing an opportunity. The Close Opportunity Competitor Required profile option (MOO_CLOSE_COMP_REQD) specifies whether a primary competitor is required on an opportunity when closing it.

You can change the default value from Y to N from both profile options so that salespeople won't have to enter a reason or a competitor when an opportunity is won or lost.

Both profile options also applies at the revenue item level.